Patent Application
20250042877
One embodiment of the present invention relates to an organic compound, an organic device, a light-emitting device, a light-emitting apparatus, a light-emitting and light-receiving device, a display apparatus, an electronic appliance, a lighting device, and an electronic device. Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. One embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Accordingly, more specific examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display apparatus, a liquid crystal display apparatus, a light-emitting apparatus, a lighting device, a power storage device, a memory device, an imaging device, a driving method thereof, and a manufacturing method thereof.
Light-emitting devices (organic EL elements or light-emitting elements) including organic compounds and utilizing electroluminescence (EL) have been put into practical use. In the basic structure of such light-emitting devices, an organic compound layer containing a light-emitting material (an EL layer) is interposed between a pair of electrodes. Carriers are injected by application of voltage to the device, and recombination energy of the carriers is used, whereby light emission can be obtained from the light-emitting material.
Such light-emitting devices are of self-luminous type; thus, they have higher visibility than liquid crystal displays and are suitable for pixels of a display. Displays using such light-emitting devices are also highly advantageous in that they require no backlight and can be fabricated to be thin and lightweight. Another feature is an extremely high response speed.
Since light-emitting layers of such light-emitting devices can be successively formed two-dimensionally, planar light emission can be obtained. This feature is difficult to realize with point light sources typified by incandescent lamps and LEDs or linear light sources typified by fluorescent lamps; thus, the light-emitting devices also have great potential as planar light sources, which can be used for lighting and the like.
Displays or lighting devices using light-emitting devices can be suitably used for a variety of electronic devices as described above, and research and development of light-emitting devices have progressed for higher efficiency and a longer lifetime.
Examples of an electron-transport material with a long lifetime for an organic electroluminescent device include an azine compound disclosed in Patent Document 1. However, further improvement has been required from a variety of aspects such as improvement in element lifetime and high-temperature resistance.
An object of one embodiment of the present invention is to provide a novel organic compound. Another object of one embodiment of the present invention is to provide a synthesis method of a novel organic compound. Another object of one embodiment of the present invention is to provide a novel electron-transport material. Another object of one embodiment of the present invention is to provide a novel organic device. Another object of one embodiment of the present invention is to provide a light-emitting element having favorable emission efficiency.
Another object of one embodiment of the present invention is to provide a compound with a high glass transition temperature Tg.
Another object of one embodiment of the present invention is to provide a compound with high stability.
Another object of one embodiment of the present invention is to provide an organic device with high heat resistance.
Another object of one embodiment of the present invention is to provide an organic device that has a long driving lifetime or less luminance degradation in high-temperature driving.
Another object of one embodiment of the present invention is to provide an organic device with a small variation in voltage in high-temperature driving.
In this specification, an organic device (also referred to as organic element) refers to any device including an organic compound (excluding a human). Examples of an organic device include a light-emitting device (also referred to as light-emitting element) and a light-receiving device (also referred to as light-receiving element). An organic device refers to, for example, a device including an organic compound layer (a thin-film layer with a thickness of several micrometers or smaller) between a pair of electrodes. Not only a device including an electrode, but also a device including an organic compound layer (e.g., a film such as an evaporation film or a coating film) over a substrate, a device including a solvent that includes an organic compound, or the like is sometimes referred to as an organic device. Alternatively, a device including a layer (e.g., a cap layer, a partition wall, a sealing layer, or a color filter) provided around an electrode is sometimes referred to as an organic device.
Note that the description of these objects does not preclude the existence of other objects. In one embodiment of the present invention, there is no need to achieve all of these objects. Other objects will be apparent from the description of the specification, the drawings, the claims, and the like, and other objects can be derived from the description of the specification, the drawings, the claims, and the like.
One embodiment of the present invention is a novel azine compound and a method for fabricating the azine compound. Another embodiment of the present invention is a novel organic device including the azine compound.
Another embodiment of the present invention is an organic compound represented by General Formula (G1) below.
In General Formula (G1), each of R1, R2, and R5 to R7 independently represents any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. R3 represents a condensed ring composed of 4 to 10 rings containing nitrogen as an element forming the ring, and R4 represents any of a substituted or unsubstituted condensed ring having 1 to 60 carbon atoms, a substituted or unsubstituted aryl group with a molecular weight of 78 or more, and a substituted or unsubstituted heteroaryl group with a molecular weight of 80 or more. Any one of A1 to A3 represents nitrogen, each of the others represents nitrogen or carbon, and in the case where each of the others represents carbon, each of A1 to A3 is independently bonded to any one of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms.
Another embodiment of the present invention is the organic compound in which in General Formula (G1), the R3 represents General Formula (G1-1), and the R4 represents any one of General Formula (G1-2) to General Formula (G1-6).
In General Formula (G1-1), any one of A11 to A22 represents nitrogen, another one represents carbon, and each of the others independently represents nitrogen or carbon. Any one of the carbons of A11 to A22 is bonded to General Formula (G1), and each of the others is bonded to any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A11 to A22 may be bonded to form a ring.
In General Formula (G1-2), any one of A41 to A48 represents carbon, and each of the others independently represents nitrogen or carbon. Any one of the carbons of A41 to A48 is bonded to General Formula (G1), and each of the others is independently bonded to any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A41 to A48 may be bonded to each other to form a ring. In General Formula (G1-3), any one of A51 to A60 represents carbon, and each of the others independently represents nitrogen or carbon. Any one of the carbons of A51 to A60 is bonded to General Formula (G1), and each of the others is independently bonded to any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A51 to A60 may be bonded to each other to form a ring. In General Formula (G1-4), any one of A61 to A68 represents carbon, and each of the others independently represents nitrogen or carbon. A69 represents nitrogen, carbon, sulfur, or oxygen. Any one of the carbons of A61 to A68 and the nitrogen of A69 is bonded to General Formula (G1), and each of the others independently represents any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A61 to A68 may be bonded to each other to form a ring. In General Formula (G1-5), any one of A71 to A80 represents carbon, and each of the others independently represents nitrogen or carbon. Any one of the carbons of A71 to A80 is bonded to General Formula (G1), and each of the others independently represents any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A71 to A80 may be bonded to each other to form a ring. In General Formula (G1-6), any one of A81 to A92 represents carbon, and each of the others independently represents nitrogen or carbon. Any one of the carbons of A81 to A92 is bonded to General Formula (G1), and each of the others independently represents any of hydrogen (including deuterium), an alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A81 to A92 may be bonded to each other to form a ring.
Another embodiment of the present invention is an organic compound represented by Structural Formula (100).
Another embodiment of the present invention is the organic compound in which the R1 and the R2 in General Formula (G1) are each a substituted or unsubstituted phenyl group.
Another embodiment of the present invention is the organic compound being represented by General Formula (G1) and having a glass transition temperature higher than or equal to 150° C.
Another embodiment of the present invention is the organic compound in which the R3 and the R4 in General Formula (G1) each have a molecular weight of 150 or more.
Another embodiment of the present invention is an organic device including any of the above organic compounds. Another embodiment of the present invention is a light-emitting apparatus including the above device, and a transistor or a substrate.
Another embodiment of the present invention is electronic appliance including any of the above organic compounds. Another embodiment of the present invention is an electronic appliance including the above light-emitting apparatus and a sensor, an operation button, a speaker, or a microphone.
Another embodiment of the present invention is a light-emitting device including an anode, a light-emitting layer, an electron-transport layer including an azine compound, a cathode, and a cap layer. The refractive index of the azine compound is lower than the refractive index of a material contained in the cap layer and the refractive index of a host material in the light-emitting layer.
Another embodiment of the present invention is a light-emitting apparatus including an anode, a hole-transport layer, a light-emitting layer, an electron-transport layer including an azine compound, and a cathode. The glass transition temperature of the azine compound is higher than the glass transition temperature of a material contained in the hole-transport layer and the glass transition temperature of a host material in the light-emitting layer.
Another embodiment of the present invention is a light-emitting apparatus including an anode, a hole-transport layer, a light-emitting layer, an electron-transport layer including an azine compound, a cathode, and a partition wall. The electron-transport layer includes a region overlapping with the partition wall. The glass transition temperature of the azine compound is higher than the glass transition temperature of a material contained in the hole-transport layer and the glass transition temperature of a host material in the light-emitting layer.
Note that these solving means do not preclude the existence of other solving means. Note that one embodiment of the present invention does not need to have all of these solving means. Other solving means will be apparent from the description of the specification, the drawings, the claims, and the like, and other solving means can be derived from the description of the specification, the drawings, the claims, and the like.
According to one embodiment of the present invention, a novel organic compound can be provided. According to another embodiment of the present invention, a novel carrier-transport material can be provided. According to another embodiment of the present invention, a novel host material can be provided. According to another embodiment of the present invention, a compound with a high glass transition temperature can be provided. According to another embodiment of the present invention, a compound with high stability can be provided. According to another embodiment of the present invention, a novel organic device can be provided. According to another embodiment of the present invention, an organic device with high emission efficiency can be fabricated. According to another embodiment of the present invention, an organic device with low power consumption can be provided. According to another embodiment of the present invention, an organic device with high reliability can be provided. According to another embodiment of the present invention, a thin film including a novel organic compound (also referred to as an organic compound layer) can be provided.
According to another embodiment of the present invention, a light-emitting apparatus, an electronic appliance, and a display apparatus each having high emission efficiency can be provided. According to another embodiment of the present invention, a light-emitting apparatus, an electronic appliance, and a display apparatus each having low power consumption can be provided. According to another embodiment of the present invention, a light-emitting apparatus, an electronic appliance, and a display apparatus each having high reliability can be provided.
Note that the description of these effects does not preclude the existence of other effects. Note that one embodiment of the present invention does not need to have all of these effects. Other effects will be apparent from the description of the specification, the drawings, the claims, and the like, and other effects can be derived from the description of the specification, the drawings, the claims, and the like.
Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the present invention is not limited to the following description, and it will be readily appreciated by those skilled in the art that modes and details of the present invention can be modified in various ways without departing from the spirit and scope of the present invention. Thus, the present invention should not be construed as being limited to the description in the following embodiments.
This embodiment describes an organic compound of one embodiment of the present invention (also referred to as a compound of the present application). The compound of one embodiment of the present invention is an organic compound including an azine skeleton (also referred to as an azine compound). An azine skeleton refers to a skeleton where one or more nitrogen atoms substitute for one or more carbon atoms of a benzene ring; for example, a pyridine skeleton, a pyrazine skeleton, a pyrimidine skeleton, a pyridazine skeleton, and a triazine skeleton can be given. A compound including an azine skeleton is an organic compound represented by General Formula (G1) below, for example.
In General Formula (G1), it is preferable that each of R1 to R7 independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms.
One of R3 and R4 preferably represents a condensed ring composed of 4 to 10 rings containing nitrogen as an element forming the ring. The other of R3 and R4 preferably represents any of a substituted or unsubstituted condensed ring having 1 to 60 carbon atoms, a substituted or unsubstituted aryl group with a molecular weight of 78 or more, and a heteroaryl group with a molecular weight of 80 or more.
When R3 or R4 includes a condensed ring, a carrier-transport property can be increased. Particularly when a condensed ring composed of three or more, preferably four or more rings is included, a carrier-transport property can be further increased. The use of a condensed ring having a helicene structure (a spiral condensed ring), such as phenanthrene, triphenylene, or dibenzoquinoxaline, can widen the band gap and increase the T1 level and the S1 level.
Any one of A1 to A3 represents nitrogen and each of the others represents nitrogen or carbon, and in the case where each of the others represents carbon, it is preferable that each of A1 to A3 be independently bonded to any one of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms.
It is preferable that each of R1 and R2 independently include an aryl group with a molecular weight of 70 or more or a heteroaryl group with a molecular weight of 70 or more. It is also preferable that each of R1 and R2 independently include an aryl group with a molecular weight of 150 or more or a heteroaryl group with a molecular weight of 150 or more.
Increasing the molecular weight of a compound and a substituent can improve the resistance (e.g., heat resistance) and the amorphous property of the compound. That is, the glass transition temperature Tg can be increased. Increasing the molecular weight can decrease the solubility of the compound in a solvent and can improve the yield by a purification step such as recrystallization. Since too large a molecular weight hinders sublimation, the molecular weights of R1 to R4 are each preferably less than or equal to 1000, further preferably less than or equal to 500. Specifically, the molecular weights of R1 to R4 are each preferably greater than or equal to 70 and less than or equal to 1000, further preferably greater than or equal to 70 and less than or equal to 500.
In addition, when a substituent includes a condensed ring or the molecular weight is increased, the resistance (e.g., stability) of the compound can be increased. Thus, as R3 or R4, it is preferable to use a condensed ring such as a naphthyl group rather than a phenyl group or to use a substituent with a larger molecular weight than a phenyl group.
Note that in this specification, the molecular weight and the atomic weight are rounded off to the nearest whole number for simplification. For example, in the case where the substituent R1 is a phenyl group, the molecular weight of R1 is C6H5=77. In the case of a naphthyl group, the molecular weight is C10H7=127. The same applies to the other substituents.
In General Formula (G1), it is preferable that one of R3 and R4 represent General Formula (G1-1) and the other of R3 and R4 represent any one of General Formula (G1-2) to General Formula (G1-6).
In General Formula (G1-1), it is preferable that any one of A11 to A22 represent nitrogen, another one represent carbon, and each of the others independently represent nitrogen or carbon. It is preferable that any one of A11 to A22 be bonded to General Formula (G1), and each of the others be bonded to any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A11 to A22 may be bonded to each other to form a ring. A structure forming a ring includes, for example, a structure where one or more benzene rings including A12 and A13 are added, and in this case, General Formula (G1-1) includes 5 or more six-membered rings. In the case where a benzene ring is formed in such a manner, a substituted or unsubstituted vinyl group is preferably included as the substituent bonded to A11 to A22. The same applies to General Formula (G1-2) to General Formula (G1-6) to be described later. Note that the structure forming a ring can be simply referred to as a structure further including a ring that includes two of A11 to A22.
In General Formula (G1-2), it is preferable that any one of A41 to A48 represent carbon, and each of the others independently represent nitrogen or carbon. It is preferable that any one of the carbons of A41 to A48 be bonded to General Formula (G1), and each of the others be independently bonded to any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A41 to A48 may be bonded to each other to form a ring.
In General Formula (G1-3), it is preferable that any one of A51 to A60 represent carbon, and each of the others independently represent nitrogen or carbon. It is preferable that any one of the carbons of A51 to A60 be bonded to General Formula (G1), and each of the others be independently bonded to any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A51 to A60 may be bonded to each other to form a ring.
In General Formula (G1-4), it is preferable that any one of A61 to A68 represent carbon, and each of the others independently represent nitrogen or carbon. It is preferable that A69 represent nitrogen, carbon, sulfur, or oxygen. It is preferable that any one of the carbons of A61 to A68 and the nitrogen of A69 be bonded to General Formula (G1), and each of the others independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A61 to A68 may be bonded to each other to form a ring.
In General Formula (G1-5), it is preferable that any one of A71 to A80 represent carbon, and each of the others independently represent nitrogen or carbon. It is preferable that any one of the carbons of A71 to A80 be bonded to General Formula (G1), and each of the others independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A71 to A80 may be bonded to each other to form a ring.
In General Formula (G1-6), it is preferable that any one of A81 to A92 represent carbon, and each of the others independently represent nitrogen or carbon. It is preferable that any one of the carbons of A81 to A92 be bonded to General Formula (G1), and each of the others independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent substituents among substituents bonded to A81 to A92 may be bonded to each other to form a ring.
In addition, the organic compound of one embodiment of the present invention is an organic compound represented by General Formula (G2) below.
In General Formula (G2), R3 to R7 and A1 to A3 can employ the above structures.
It is preferable that each of R8 to R17 independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent groups among R8 to R17 may be bonded to each other to form a ring.
Alternatively, the organic compound of one embodiment of the present invention is an organic compound represented by General Formula (G3) below.
In General Formula (G3), R1 to R7 and A1 to A3 can employ the above structures.
It is preferable that each of R18 to R21 independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent groups among R18 to R21 may be bonded to each other to form a ring. Furthermore, m represents 1 or 2. The bonding position of R4 may be any of a meta-position, a para-position, and an ortho-position; the sublimation temperature can be decreased in the case of the meta-position, and Tg can be increased in the case of the para-position.
Alternatively, the organic compound of one embodiment of the present invention is an organic compound represented by General Formula (G4) below.
In General Formula (G4), R1 to R7 and A1 to A3 can employ the above structures.
It is preferable that each of R18 to R25 independently represent any of hydrogen (including deuterium), a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, a substituted or unsubstituted aryl group having 1 to 60 carbon atoms, and a substituted or unsubstituted heteroaryl group having 1 to 60 carbon atoms. Adjacent groups among R18 to R25 may be bonded to each other to form a ring. Furthermore, m represents 1 or 2. Furthermore, n represents 1 or 2. The bonding positions of R3 and R4 may each be any of a meta-position, a para-position, and an ortho-position; the sublimation temperature can be decreased in the case of the meta-position, and Tg can be increased in the case of the para-position.
The glass transition temperature Tg of the compound of one embodiment of the present invention is preferably higher than or equal to 100° C. The glass transition temperature Tg of the compound of one embodiment of the present invention is higher than or equal to 120° C., preferably higher than or equal to 130° C., further preferably higher than or equal to 140° C., still further preferably higher than or equal to 150° C., particularly desirably higher than or equal to 160° C.
The solubility of the compound of one embodiment of the present invention is preferably higher than or equal to 0% and lower than 5%. In this specification, the solubility (weight %) is evaluated as follows. When a solute A (g) and a solvent B (g) are put into a glass container and no precipitate is visually observed, the solubility is determined to be higher than or equal to (A/(A+B)×100) %, and when a precipitate is visually observed, the solubility is determined to be lower than (A/(A+B)×100) %.
Note that for A1 to A92 or R1 to R25 in General Formulae (G1) to (G4), a combination of the above structures (e.g., the substituent structure and the molecular weight) may be employed. For example, it is preferable to combine a structure where “R3 and R4 each include a condensed ring composed of three or more rings and R4 contains nitrogen” and a structure where “A1 to A3 are all nitrogen and R1 and R2 each have a molecular weight of 70 or more”. An appropriate combination of a plurality of structures, without limited to the above examples, can bring a synergistic effect enabling a higher glass transition temperature Tg, higher stability, and more stable film quality in a thin film state, for example.
In the above General Formulae (G1) to (G4), specific examples of the substituted or unsubstituted alkyl group having 1 to 10 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, an isopentyl group, a sec-pentyl group, a tert-pentyl group, a neopentyl group, a hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, a neohexyl group, a 3-methylpentyl group, a 2-methylpentyl group, a 2-ethylbutyl group, a 1,2-dimethylbutyl group, and a 2,3-dimethylbutyl group.
In General Formulae (G1) to (G4), specific examples of a substituted or unsubstituted aryl group having 6 to 60 carbon atoms and a substituted or unsubstituted heteroaryl group having 2 to 50 carbon atoms include a substituted or unsubstituted phenyl group, a substituted or unsubstituted biphenyl group, a substituted or unsubstituted terphenyl group, a substituted or unsubstituted fluorenyl group, a substituted or unsubstituted spirobifluorenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted anthracenyl group, a substituted or unsubstituted phenanthryl group, a substituted or unsubstituted fluoranthenyl group, a substituted or unsubstituted pyrenyl group, a substituted or unsubstituted chrysenyl group, a substituted or unsubstituted triphenylenyl group, a substituted or unsubstituted perylenyl group, a substituted or unsubstituted indenyl group, a substituted or unsubstituted banzindenyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted indolyl group, a substituted or unsubstituted carbazolyl group, a substituted or unsubstituted furanyl group, a substituted or unsubstituted benzofuranyl group, a substituted or unsubstituted dibenzofuranyl group, a substituted or unsubstituted thiophenyl group, a substituted or unsubstituted benzothiophenyl group, a substituted or unsubstituted dibenzothiophenyl group, a substituted or unsubstituted imidazolyl group, a substituted or unsubstituted benzimidazolyl group, a substituted or unsubstituted triazolyl group, a substituted or unsubstituted oxazolyl group, a substituted or unsubstituted oxadiazolyl group, a substituted or unsubstituted thiazolyl group, a substituted or unsubstituted thiaziazolyl group, a substituted or unsubstituted pyrazolyl group, a substituted or unsubstituted pyridyl group, a substituted or unsubstituted pyrimidyl group, a substituted or unsubstituted pyridazyl group, a substituted or unsubstituted triazinyl group, a substituted or unsubstituted quinolinyl group, a substituted or unsubstituted indolocarbazolyl group, a substituted or unsubstituted benzocarbazolyl group, a substituted or unsubstituted quinoxalinyl group, and a substituted or unsubstituted dibenzoquinoxalinyl group. Note that the bonding position can be any possible one. More Specifically, a substituent represented by any of (R-1) to (R-112) is preferable. The substituent represented by any of (R-1) to (R-112) may further include a substituent.
When used for a light-emitting device, the compound of one embodiment of the present invention is preferably used in a thin film (also referred to as an organic compound layer). A thin film including the organic compound of one embodiment of the present invention can be suitably used for a charge-adjustment layer, a charge-generation layer, a light-emitting layer, a hole-injection layer, a hole-transport layer, an electron-transport layer, an electron-injection layer, or a cap layer in the light-emitting device. In addition, the organic compound of one embodiment of the present invention can be used also for a non-light-emitting device. As the non-light-emitting device, a device such as a light-receiving device can be given, for example.
Note that the detailed structure where the organic compound of one embodiment of the present invention is used for a light-emitting device or a light-receiving device will be described in detail in Embodiment 2 or the like to be described later.
Next, specific examples of an organic compound having a structure represented by any of General Formulae (G1) to (G4) and an organic compound that can be used for a light-emitting device are described below.
A variety of reactions can be employed as a method for synthesizing the compound of one embodiment of the present invention. For example, synthesis reactions described below enable the synthesis of the compound of one embodiment of the present invention represented by General Formula (G1). Note that the method for synthesizing the compound of one embodiment of the present invention is not limited to the synthesis methods below.
This embodiment describes a method for synthesizing the organic compound of one embodiment of the present invention represented by General Formula (G1) below.
In General Formula (G1), any of the above-described elements or substituents can be used as A1 to A3 or R1 to R7.
The organic compound represented by General Formula (G1) can be synthesized as shown in Synthesis Schemes (a-1) to (a-5) below.
First, according to Reaction Formula (a-1), a compound 1 including an azine skeleton and a compound 2 including R1 are coupled with each other, whereby a compound 3 can be obtained. Next, according to Reaction Formula (a-2), the compound 3 and a compound 4 including R2 are coupled with each other, whereby a compound 5 can be obtained. Then, according to Reaction Formula (a-3), the compound 5 and a compound 6 are coupled with each other, whereby a compound 7 can be obtained. Next, according to Reaction Formula (a-4), the compound 7 and a compound 8 including R3 are coupled with each other, whereby a compound 9 can be obtained. Then, according to Reaction Formula (a-5), the compound 9 and a compound 10 including R4 are coupled with each other, whereby the compound represented by General Formula (G1) can be obtained.
In Synthesis Schemes (a-1) to (a-5), any of the above-described elements or substituents can be used as A1 to A3 or R1 to R7.
In Synthesis Schemes (a-1) to (a-5), each of X1 to X3 represents a halogen group (including chlorine, for example). In addition, each of B1 to B5 represents a boronic acid. Note that without limitation to these examples, each of X1 to X3 and B1 to B5 may independently be chlorine, bromine, iodine, a triflate group, an organoboron group, a boronic acid, organoaluminum, organozirconium, organozinc, an organotin group, or the like. Note that in the case where R3 and R4 have different substituent structures in General Formula (G1), it is preferable that one of X4 and X5 be chlorine and the other be bromine or iodine. When one of X4 and X5 is chlorine and the other is bromine or iodine, the coupling reaction proceeds preferentially in X4 or X5 which is bromine or iodine, so that General Formula (G1) can be obtained with a high yield and high purity. In the case where R3 and R4 have the same substituent structure in General Formula (G1), it is preferable that X4 and X5 be the same halogen or each of X4 and X5 be independently bromine or iodine; in this case, by making two equivalents of the compound 8 react with the compound 7, General Formula (G1) can be obtained from the compound 7 only in one step.
Synthesis Schemes (a-1) to (a-5) can be performed by the Suzuki-Miyaura coupling reaction, for example. Examples of a palladium (Pd) catalyst in this case include palladium(II) acetate, tetrakis(triphenylphosphine)palladium(0), and bis(triphenylphosphine)palladium(II) dichloride. Examples of a ligand of the palladium catalyst include tri (ortho-tolyl)phosphine, triphenylphosphine, and tricyclohexylphosphine.
Examples of a base that can be used in the reactions in Synthesis Schemes (a-1) to (a-5) include organic bases such as sodium-tert-butoxide and inorganic bases such as potassium carbonate, sodium carbonate, potassium phosphate, and potassium acetate.
Examples of a solvent that can be used in the reactions in Synthesis Schemes (a-1) to (a-5) include a mixed solvent of toluene and water; a mixed solvent of toluene, alcohol such as ethanol, and water; a mixed solvent of xylene and water; a mixed solvent of xylene, alcohol such as ethanol, and water; a mixed solvent of benzene and water; a mixed solvent of benzene, alcohol such as ethanol, and water; and a mixed solvent of water and an ether such as diethylene glycol dimethyl ether. Note that a mixed solvent of toluene and water, a mixed solvent of toluene, ethanol, and water, or a mixed solvent of water and an ether such as diethylene glycol dimethyl ether is further preferable.
Note that any palladium catalyst, ligand, base, and solvent other than the above examples may be used.
Alternatively, R1 to R7 may each be deuterium. Substituents of A1 to A3 or substituents of R1 to R7 may each be deuterium. In that case, the coupling reaction is performed using a compound obtained by deuteration of the compound 1, the compound 2, the compound 4, the compound 6, the compound 8, or the compound 10. Examples of a solvent that can be used in a reaction performing deuteration include benzene-d6, toluene-d8, xylene-d10, and heavy water. Examples of a catalyst that can be used include molybdenum(V) chloride, tungsten(VI) chloride, niobium(V) chloride, tantalum(V) chloride, aluminum(III) chloride, titanium(IV) chloride, and tin (IV) chloride. However, the solvent and the catalyst are not limited to the above.
For example, in the case of manufacturing a compound of General Formula (G1) where R3 is an aryl group and R4 to R7 are each hydrogen, a compound 11 where X6 is halogen (including chlorine, for example) and X7 to X10 are each hydrogen is coupled with a compound 12. Similarly, in the case of manufacturing a compound where R3 and R4 are each an aryl group and R5 to R7 are each hydrogen, the compound 11 where X6 and X7 are each halogen and X8 to X10 are each hydrogen, the compound 12, and a compound 13 are coupled sequentially. Note that the compound 11 can be synthesized in a manner similar to that of the compound 7 using Reaction Formulae (a-1) to (a-3) in the synthesis method 1.
Each of X6 to X10 and B6 to B10 independently represents hydrogen, chlorine, bromine, iodine, a triflate group, an organoboron group, a boronic acid, organoaluminum, organozirconium, organozinc, an organotin group, or the like.
As the conditions (a palladium catalyst, a solvent, and the like) used in the coupling reactions, the conditions in the method shown in Reaction Formulae (a-1) to (a-5) can be used.
Note that a compound represented by General Formula (G2) or General Formula (G3) can also be synthesized by a similar synthesis method.
Some of the compounds represented by Structural Formulae (100) to (450) which are manufactured by the above synthesis method will be described later as examples. Needless to say, the compounds that are not described as examples can be manufactured by coupling any of the above substituents (R-1) to (R-112) with R1 to R7 in Reaction Formulae (a-1) to (a-5) or R1 to R7 in (b-1) as appropriate.
Note that the above synthesis method is an example and the compound of the present application can be manufactured by another synthesis method.
In this embodiment, structures of a light-emitting device using the organic compound described in Embodiment 1 will be described with reference to
A basic structure of a light-emitting device is described.
The charge-generation layer 106 has a function of injecting electrons to one of the EL layers (103a or 103b) and injecting holes to the other of the EL layers (103b or 103a) when a potential difference is generated between the first electrode 101 and the second electrode 102. Thus, when voltage is applied such that the potential of the first electrode 101 is higher than that of the second electrode 102 in
Note that in terms of light extraction efficiency, the charge-generation layer 106 preferably has a light-transmitting property with respect to visible light (specifically, the charge-generation layer 106 preferably has a visible light transmittance of 40% or higher). The charge-generation layer 106 functions even when having lower conductivity than the first electrode 101 and the second electrode 102. The compound of the present application can also be used for a layer where electrons are injected from the charge-generation layer. In that case, it is preferable to use a mixed layer or a stacked-layer structure of a Li compound such as Li metal or lithium oxide and the compound of the present application.
The light-emitting layers 113 included in the EL layers (103, 103a, and 103b) each contain an appropriate combination of a light-emitting substance and a plurality of substances, so that fluorescent light or phosphorescent light of a desired emission color can be obtained. Furthermore, the light-emitting layer 113 may have a stacked-layer structure having different emission colors. In that case, light-emitting substances and other substances are different between the stacked light-emitting layers. Furthermore, a structure where different emission colors can be obtained from the plurality of EL layers (103a and 103b) illustrated in
In addition, the light-emitting device of one embodiment of the present invention can have an optical micro resonator (microcavity) structure with the first electrode 101 being a reflective electrode and the second electrode 102 being a semi-transmissive and semi-reflective electrode illustrated in
Note that when the first electrode 101 of the light-emitting device is a reflective electrode having a stacked-layer structure of a reflective conductive material and a light-transmitting conductive material (a transparent conductive film), optical adjustment can be performed by adjusting the thickness of the transparent conductive film. Specifically, when the wavelength 2 of light obtained from the light-emitting layer 113 is 1, the optical path length between the first electrode 101 and the second electrode 102 (the product of the thickness and the refractive index) is preferably adjusted to be mλ/2 (note that m is an integer greater than or equal to 1) or a neighborhood thereof.
To amplify desired light (wavelength: 2) obtained from the light-emitting layer 113, it is preferable to adjust each of the optical path length from the first electrode 101 to a region where the desired light is obtained in the light-emitting layer 113 (light-emitting region) and the optical path length from the second electrode 102 to the region where the desired light is obtained in the light-emitting layer 113 (light-emitting region) to be (2m′+1)λ/4 (note that m′ is an integer greater than or equal to 1) or a neighborhood thereof. Note that the light-emitting region here refers to a region where holes and electrons are recombined in the light-emitting layer 113.
By performing such optical adjustment, the spectrum of specific monochromatic light obtained from the light-emitting layer 113 can be narrowed and light emission with high color purity can be obtained.
Note that in the above case, the optical path length between the first electrode 101 and the second electrode 102 is, to be exact, the total thickness from a reflective region in the first electrode 101 to a reflective region in the second electrode 102. However, it is difficult to precisely determine the reflective regions in the first electrode 101 and the second electrode 102; thus, it is assumed that the above effect can be sufficiently obtained wherever the reflective regions may be set in the first electrode 101 and the second electrode 102. Furthermore, the optical path length between the first electrode 101 and the light-emitting layer from which the desired light is obtained is, to be exact, the optical path length between the reflective region in the first electrode 101 and the light-emitting region in the light-emitting layer from which the desired light is obtained. However, it is difficult to precisely determine the reflective region in the first electrode 101 and the light-emitting region in the light-emitting layer that emits the desired light; thus, it is assumed that the above effect can be sufficiently obtained wherever the reflective region and the light-emitting region may be set in the first electrode 101 and the light-emitting layer that emits the desired light, respectively.
The light-emitting device illustrated in
A light-emitting device illustrated in
In the above light-emitting device of one embodiment of the present invention, at least one of the first electrode 101 and the second electrode 102 is an electrode having a light-transmitting property (a transparent electrode, a semi-transmissive and semi-reflective electrode, or the like). In the case where the electrode having a light-transmitting property is a transparent electrode, the visible light transmittance of the transparent electrode is higher than or equal to 40%. In the case where the electrode having a light-transmitting property is a semi-transmissive and semi-reflective electrode, the visible light reflectance of the semi-transmissive and semi-reflective electrode is higher than or equal to 20% and lower than or equal to 80%, preferably higher than or equal to 40% and lower than or equal to 70%. The resistivity of these electrodes is preferably lower than or equal to 1×10−2 Ωcm.
In the case where one of the first electrode 101 and the second electrode 102 is an electrode having a reflecting property (a reflective electrode) in the above light-emitting device of one embodiment of the present invention, the visible light reflectance of the electrode having a reflecting property is higher than or equal to 40% and lower than or equal to 100%, preferably higher than or equal to 70% and lower than or equal to 100%. The resistivity of this electrode is preferably lower than or equal to 1×10−2 Ωcm.
Although
Next, a specific structure of the light-emitting device of one embodiment of the present invention will be described. Here, description is made with reference to
As materials for forming the first electrode 101 and the second electrode 102, any of the following materials can be used in an appropriate combination as long as the functions of the both electrodes described above can be fulfilled. For example, a metal, an alloy, an electrically conductive compound, and a mixture of these can be used as appropriate. Specifically, an In—Sn oxide (also referred to as ITO), an In—Si—Sn oxide (also referred to as ITSO), an In—Zn oxide, and an In—W—Zn oxide are given. In addition, it is also possible to use a metal such as aluminum (Al), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), gallium (Ga), zinc (Zn), indium (In), tin (Sn), molybdenum (Mo), tantalum (Ta), tungsten (W), palladium (Pd), gold (Au), platinum (Pt), silver (Ag), yttrium (Y), or neodymium (Nd) or an alloy containing an appropriate combination of any of these metals. It is also possible to use an element belonging to Group 1 or Group 2 in the periodic table, which is not listed above as an example (for example, lithium (Li), cesium (Cs), calcium (Ca), or strontium (Sr)), a rare earth metal such as europium (Eu) or ytterbium (Yb), an alloy containing an appropriate combination of any of these elements, graphene, or the like.
In the light-emitting device illustrated in
The hole-injection layers (111, 111a, and 111b) are layers which inject holes from the first electrode 101 serving as the anode and the charge-generation layers (106, 106a, and 106b) to the EL layers (103, 103a, and 103b) and contain an organic acceptor material and a material having a high hole-injection property.
The organic acceptor material in one organic compound allows holes to be generated in another organic compound whose HOMO level is close to the LUMO (lowest unoccupied molecular orbital) level of the organic acceptor material when charge separation is caused between the organic acceptor material and the organic compound. Thus, as the organic acceptor material, a compound having an electron-withdrawing group (a halogen group or a cyano group), such as a quinodimethane derivative, a chloranil derivative, or a hexaazatriphenylene derivative, can be used. For example, it is possible to use 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), 3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane, chloranil, 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (abbreviation: HAT-CN), 1,3,4,5,7,8-hexafluorotetracyano-naphthoquinodimethane (abbreviation: F6-TCNNQ), or 2-(7-dicyanomethylen-1,3,4,5,6,8,9,10-octafluoro-7H-pyren-2-ylidene) malononitrile. Note that among organic acceptor materials, a compound in which electron-withdrawing groups are bonded to condensed aromatic rings each having a plurality of heteroatoms, such as HAT-CN, is particularly preferred because it has a high acceptor property and stable film quality against heat. Specific examples include α,α′,α″-1,2,3-cyclopropanetriylidenetris[4-cyano-2,3,5,6-tetrafluorobenzeneacetonitrile], α,α′,α″-1,2,3-cyclopropanetriylidenetris[2,6-dichloro-3,5-difluoro-4-(trifluoromethyl)benzeneacetonitrile], and α,α′,α″-1,2,3-cyclopropanetriylidenetris[2,3,4,5,6-pentafluorobenzeneacetonitrile].
As the material having a high hole-injection property, an oxide of a metal belonging to Group 4 to Group 8 in the periodic table (e.g., a transition metal oxide such as a molybdenum oxide, a vanadium oxide, a ruthenium oxide, a tungsten oxide, or a manganese oxide) can be used. As specific examples, a molybdenum oxide, a vanadium oxide, a niobium oxide, a tantalum oxide, a chromium oxide, a tungsten oxide, a manganese oxide, and a rhenium oxide are given. In particular, a molybdenum oxide is preferable because it is stable in the air, has a low hygroscopic property, and is easily handled. It is also possible to use phthalocyanine (abbreviation: H2Pc), a phthalocyanine-based compound such as copper phthalocyanine (abbreviation: CuPc), or the like.
In addition to the above materials, it is also possible to use an aromatic amine compound, which is a low molecular compound, such as 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: MTDATA), 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), N,N′-bis {4-[bis(3-methylphenyl)amino]phenyl}-N,N′-diphenylbiphenyl)-4,4′-diamine (abbreviation: DNTPD), 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), or 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1).
It is also possible to use a high molecular compound (an oligomer, a dendrimer, a polymer, or the like) such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl) methacrylamide] (abbreviation: PTPDMA), or poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation: Poly-TPD). It is also possible to use a high molecular compound to which acid such as poly(3,4-ethylenedioxythiophene)/polystyrenesulfonic acid (abbreviation: PEDOT/PSS) or polyaniline/polystyrenesulfonic acid (abbreviation: PAni/PSS) is added.
As the material having a high hole-injection property, a mixed material containing a hole-transport material and the above-described organic acceptor material (an electron-accepting material) can be used. In that case, the organic acceptor material extracts electrons from the hole-transport material, so that holes are generated in the hole-injection layer 111 and the holes are injected into the light-emitting layer 113 through the hole-transport layer 112. Note that the hole-injection layer 111 may be formed as a single layer of a mixed material containing the hole-transport material and the organic acceptor material (an electron-accepting material), or may be formed by stacking a layer containing the hole-transport material and a layer containing the organic acceptor material (the electron-accepting material).
The hole-transport material is preferably a substance having a hole mobility higher than or equal to 1×10−6 cm2/Vs in the case where the square root of the electric field strength [V/cm] is 600. Note that any other substance can be used as long as the substance has a hole-transport property higher than an electron-transport property.
As the hole-transport material, a material having a high hole-transport property such as a compound having a π-electron rich heteroaromatic ring (e.g., a carbazole derivative, a furan derivative, or a thiophene derivative) or an aromatic amine (an organic compound having an aromatic amine skeleton), is preferable. The compound in Embodiment 1 has a hole-transport property and thus can be used as a hole-transport material.
Examples of the above carbazole derivative (an organic compound having a carbazole ring) include a bicarbazole derivative (e.g., a 3,3′-bicarbazole derivative) and an aromatic amine having a carbazolyl group.
Specific examples of the above bicarbazole derivative (e.g., a 3,3′-bicarbazole derivative) include 3,3′-bis(9-phenyl-9H-carbazole) (abbreviation: PCCP), 9,9′-bis(biphenyl-4-yl)-3,3′-bi-9H-carbazole (abbreviation: BisBPCz), 9,9′-bis(biphenyl-3-yl)-3,3′-bi-9H-carbazole (abbreviation: BismBPCz), 9-(biphenyl-3-yl)-9′-(biphenyl-4-yl)-9H,9′H-3,3′-bicarbazole (abbreviation: mBPCCBP), and 9-(2-naphthyl)-9′-phenyl-9H,9′H-3,3′-bicarbazole (abbreviation: BNCCP).
Specific examples of the aromatic amine having a carbazolyl group include 4-phenyl-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBA1BP), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9-phenyl-9H-carbazol-3-amine (abbreviation: PCBiF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-2-amine (abbreviation: PCBBiF), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-bis(9,9-dimethyl-9H-fluoren-2-yl)amine (abbreviation: PCBFF), N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-dimethyl-9H-fluoren-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-(9,9-dimethyl-9H-fluoren-2-yl)-9,9-dimethyl-9H-fluoren-4-amine, N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-diphenyl-9H-fluoren-2-amine, N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9-diphenyl-9H-fluoren-4-amine, N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9′-spirobi (9H-fluoren)-2-amine, N-(biphenyl-4-yl)-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-9,9′-spirobi (9H-fluoren)-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[1,1′: 3′,1″-terphenyl-4-yl]-9,9-dimethyl-9H-fluoren-2-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[1,1′: 4′,1″-terphenyl-4-yl]-9,9-dimethyl-9H-fluoren-2-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[1,1′: 3′,1″-terphenyl-4-yl]-9,9-dimethyl-9H-fluoren-4-amine, N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[1,1′: 4′,1″-terphenyl-4-yl]-9,9-dimethyl-9H-fluoren-4-amine, 4,4′-diphenyl-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBBi1BP), 4-(1-naphthyl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBANB), 4,4′-di(1-naphthyl)-4″-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBNBB), 4-phenyldiphenyl-(9-phenyl-9H-carbazol-3-yl)amine (abbreviation: PCA1BP), N,N′-bis(9-phenylcarbazol-3-yl)-N,N′-diphenylbenzene-1,3-diamine (abbreviation: PCA2B), N,N′,N″-triphenyl-N,N′,N″-tris(9-phenylcarbazol-3-yl)benzene-1,3,5-triamine (abbreviation: PCA3B), 9,9-dimethyl-N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]fluoren-2-amine (abbreviation: PCBAF), N-phenyl-N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]spiro-9,9′-bifluoren-2-amine (abbreviation: PCBASF), 3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA1), 3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzPCA2), 3-[N-(1-naphthyl)-N-(9-phenylcarbazol-3-yl)amino]-9-phenylcarbazole (abbreviation: PCzPCN1), 3-[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA1), 3,6-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-9-phenylcarbazole (abbreviation: PCzDPA2), 3,6-bis[N-(4-diphenylaminophenyl)-N-(1-naphthyl)amino]-9-phenylcarbazole (abbreviation: PCzTPN2), 2-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]spiro-9,9′-bifluorene (abbreviation: PCASF), N-[4-(9H-carbazol-9-yl)phenyl]-N-(4-phenyl)phenylaniline (abbreviation: YGA1BP), N,N′-bis[4-(carbazol-9-yl)phenyl]-N,N′-diphenyl-9,9-dimethylfluorene-2,7-diamine (abbreviation: YGA2F), and 4,4′,4″-tris(carbazol-9-yl)triphenylamine (abbreviation: TCTA).
In addition to the above, other examples of the carbazole derivative include 3-[4-(9-phenanthryl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPPn), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 1,3-bis(N-carbazolyl)benzene (abbreviation: mCP), 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP), 3,6-bis(3,5-diphenylphenyl)-9-phenylcarbazole (abbreviation: CzTP), 1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB), and 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA).
Specific examples of the furan derivative (an organic compound having a furan ring) include 4,4′,4″-(benzene-1,3,5-triyl)tri (dibenzofuran) (abbreviation: DBF3P-II) and 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II).
Specific examples of the thiophene derivative (the organic compound having a thiophene ring) include 4,4′,4″-(benzene-1,3,5-triyl)tri (dibenzothiophene) (abbreviation: DBT3P-II), 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), and 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV).
Specific examples of the aromatic amine include 4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB or α-NPD), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-biphenyl-4,4′-diamine (abbreviation: TPD), 4,4′-bis[N-(spiro-9,9′-bifluoren-2-yl)-N-phenylamino]biphenyl (abbreviation: BSPB), 4-phenyl-4′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: BPAFLP), 4-phenyl-3′-(9-phenylfluoren-9-yl)triphenylamine (abbreviation: mBPAFLP), N-(9,9-dimethyl-9H-fluoren-2-yl)-N-{9,9-dimethyl-2-[N-phenyl-N-(9,9-dimethyl-9H-fluoren-2-yl)amino]-9H-fluoren-7-yl}phenylamine (abbreviation: DFLADFL), N-(9,9-dimethyl-2-diphenylamino-9H-fluoren-7-yl)diphenylamine (abbreviation: DPNF), 2-[N-(4-diphenylaminophenyl)-N-phenylamino]spiro-9,9′-bifluorene (abbreviation: DPASF), 2,7-bis[N-(4-diphenylaminophenyl)-N-phenylamino]-spiro-9,9′-bifluorene (abbreviation: DPA2SF), 4,4′,4″-tris[N-(1-naphthyl)-N-phenylamino]triphenylamine (abbreviation: 1′-TNATA), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA), 4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine (abbreviation: m-MTDATA), N,N′-di(p-tolyl)-N,N′-diphenyl-p-phenylenediamine (abbreviation: DTDPPA), 4,4′-bis[N-(4-diphenylaminophenyl)-N-phenylamino]biphenyl (abbreviation: DPAB), DNTPD, 1,3,5-tris[N-(4-diphenylaminophenyl)-N-phenylamino]benzene (abbreviation: DPA3B), N-(4-biphenyl)-6,N-diphenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BnfABP), N,N-bis(4-biphenyl)-6-phenylbenzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf), 4,4′-bis(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)-4″-phenyltriphenylamine (abbreviation: BnfBB1BP), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-6-amine (abbreviation: BBABnf(6)), N,N-bis(4-biphenyl)benzo[b]naphtho[1,2-d]furan-8-amine (abbreviation: BBABnf(8)), N,N-bis(4-biphenyl)benzo[b]naphtho[2,3-d]furan-4-amine (abbreviation: BBABnf(II)(4)), N,N-bis[4-(dibenzofuran-4-yl)phenyl]-4-amino-p-terphenyl (abbreviation: DBfBB1TP), N-[4-(dibenzothiophen-4-yl)phenyl]-N-phenyl-4-biphenylamine (abbreviation: ThBA1BP), 4-(2-naphthyl)-4′,4″-diphenyltriphenylamine (abbreviation: BBAβNB), 4-[4-(2-naphthyl)phenyl]-4′,4″-diphenyltriphenylamine (abbreviation: BBAβNBi), 4,4′-diphenyl-4″-(6;1′-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNBNB), 4,4′-diphenyl-4″-(7; l′-binaphthyl-2-yl)triphenylamine (abbreviation: BBAαNBNB-03), 4,4′-diphenyl-4″-(7-phenyl) naphthyl-2-yltriphenylamine (abbreviation: BBAPβNB-03), 4,4′-diphenyl-4″-(6;2′-binaphthyl-2-yl)triphenylamine BBA(βN2)B), (abbreviation: 4,4′-diphenyl-4″-(7;2′-binaphthyl-2-yl)triphenylamine (abbreviation: BBA(βN2)B-03), 4,4′-diphenyl-4″-(4;2′-binaphthyl-1-yl)triphenylamine (abbreviation: BBAβNαNB), 4,4′-diphenyl-4″-(5;2′-binaphthyl-1-(abbreviation: BBAβNαNB-02), 4-(4-biphenylyl)-4′-(2-naphthyl)-4″-yl)triphenylamine phenyltriphenylamine (abbreviation: TPBiAβNB), 4-(3-biphenylyl)-4′-[4-(2-naphthyl)phenyl]-4″-phenyltriphenylamine (abbreviation: mTPBiAβNBi), 4-(4-biphenylyl)-4′-[4-(2-naphthyl)phenyl]-4″-phenyltriphenylamine (abbreviation: TPBiAβNBi), 4-phenyl-4′-(1-naphthyl)-triphenylamine (abbreviation: αNBA1BP), 4,4′-bis(1-naphthyl)triphenylamine (abbreviation: αNBB1BP), 4,4′-diphenyl-4″-[4′-(carbazol-9-yl)biphenyl-4-yl]triphenylamine (abbreviation: YGTBi1BP), 4′-[4-(3-phenyl-9H-carbazol-9-yl)phenyl]tris(biphenyl-4-yl)amine (abbreviation: YGTBi1BP-02), 4-[4′-(carbazol-9-yl)biphenyl-4-yl]-4′-(2-naphthyl)-4″-phenyltriphenylamine (abbreviation: YGTBiβNB), N-[4-(9-phenyl-9H-carbazol-3-yl)phenyl]-N-[4-(1-naphthyl)phenyl]-9,9′-spirobi[9H-fluoren]-2-amine (abbreviation: PCBNBSF), N,N-bis(biphenyl-4-yl)-9,9′-spirobi[9H-fluoren]-2-amine (abbreviation: BBASF), N,N-bis(biphenyl-4-yl)-9,9′-spirobi[9H-fluoren]-4-amine (abbreviation: BBASF (4)), N-(biphenyl-2-yl)-N-(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi[9H-fluoren]-4-amine (abbreviation: oFBiSF), N-(4-biphenyl)-N-(9,9-dimethyl-9H-fluoren-2-yl)dibenzofuran-4-amine (abbreviation: FrBiF), N-[4-(1-naphthyl)phenyl]-N-[3-(6-phenyldibenzofuran-4-yl)phenyl]-1-naphthylamine (abbreviation: mPDBfBNBN), 4-phenyl-4′-[4-(9-phenylfluoren-9-yl)phenyl]triphenylamine (abbreviation: BPAFLBi), N, N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-4-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-3-amine, N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-2-amine, and N,N-bis(9,9-dimethyl-9H-fluoren-2-yl)-9,9′-spirobi-9H-fluoren-1-amine.
Alternatively, it is also possible to use, as the hole-transport material, a high molecular compound (e.g., an oligomer, a dendrimer, or a polymer) such as poly(N-vinylcarbazole) (abbreviation: PVK), poly(4-vinyltriphenylamine) (abbreviation: PVTPA), poly[N-(4-{N′-[4-(4-diphenylamino)phenyl]phenyl-N′-phenylamino}phenyl) methacrylamide] (abbreviation: PTPDMA), poly[N,N′-bis(4-butylphenyl)-N,N′-bis(phenyl)benzidine] (abbreviation: Poly-TPD), or the like. It is also possible to use a high molecular compound to which acid such as poly(3,4-ethylenedioxythiophene)/polystyrenesulfonic acid (abbreviation: PEDOT/PSS) or polyaniline/polystyrenesulfonic acid (abbreviation: PAni/PSS) is added.
Note that the hole-transport material is not limited to the above, and one of or a combination of various known materials may be used as the hole-transport material.
Note that the hole-injection layers (111, 111a, and 111b) can be formed by any of various known film formation methods, and can be formed by a vacuum evaporation method, for example.
The hole-transport layers (112, 112a, and 112b) are layers transporting the holes, which are injected from the first electrode 101 by the hole-injection layers (111, 111a, and 111b), to the light-emitting layers (113, 113a, and 113b). Note that the hole-transport layers (112, 112a, and 112b) are each a layer containing a hole-transport material. Thus, for the hole-transport layers (112, 112a, and 112b), a hole-transport material that can be used for the hole-injection layers (111, 111a, and 111b) can be used.
Note that in the light-emitting device of one embodiment of the present invention, the organic compound used for the hole-transport layers (112, 112a, and 112b) can also be used for the light-emitting layers (113, 113a, 113b, and 113c). The use of the same organic compound for the hole-transport layers (112, 112a, and 112b) and the light-emitting layers (113, 113a, 113b, and 113c) is preferable, in which case holes can be efficiently transported from the hole-transport layers (112, 112a, and 112b) to the light-emitting layers (113, 113a, 113b, and 113c).
The light-emitting layers (113, 113a, 113b, and 113c) are each a layer containing a light-emitting substance. Note that as a light-emitting substance that can be used for the light-emitting layers (113, 113a, 113b, and 113c), a substance whose emission color is blue, violet, bluish violet, green, yellowish green, yellow, orange, red, or the like can be used as appropriate. In the case where a plurality of light-emitting layers are provided, different light-emitting substances are used for the light-emitting layers; thus, different emission colors can be exhibited (for example, complementary emission colors are combined to obtain white light emission). Furthermore, one light-emitting layer may have a stacked-layer structure containing different light-emitting substances.
The light-emitting layers (113, 113a, 113b, and 113c) may each contain one or more kinds of organic compounds (e.g., a host material) in addition to a light-emitting substance (a guest material).
In the case where a plurality of host materials are used in the light-emitting layers (113, 113a, 113b, and 113c), a second host material that is additionally used is preferably a substance having a larger energy gap than a known guest material and a first host material. Preferably, the lowest singlet excitation energy level (S1 level) of the second host material is higher than the S1 level of the first host material, and the lowest triplet excitation energy level (T1 level) of the second host material is higher than the T1 level of the guest material. Furthermore, the lowest triplet excitation energy level (T1 level) of the second host material is preferably higher than the T1 level of the first host material. With such a structure, an exciplex can be formed by the two kinds of host materials. To form an exciplex efficiently, it is particularly preferable to combine a compound that easily accepts holes (a hole-transport material) and a compound that easily accepts electrons (an electron-transport material). With this structure, high efficiency, low voltage, and a long lifetime can be achieved at the same time.
As an organic compound used as the above host material (including the first host material and the second host material), organic compounds such as the hole-transport materials that can be used for the hole-transport layers (112, 112a, and 112b) described above and electron-transport materials that can be used for electron-transport layers (114, 114a, and 114b) described later can be used as long as they satisfy requirements for the host material used in the light-emitting layer.
Another example is an exciplex formed by a plurality of kinds of organic compounds (the first host material and the second host material). An exciplex (also referred to as Exciplex) whose excited state is formed by a plurality of kinds of organic compounds has an extremely small difference between the S1 level and the T1 level and functions as a TADF material capable of converting triplet excitation energy into singlet excitation energy. As a combination of the plurality of kinds of organic compounds forming an exciplex, for example, it is preferable that one have a π-electron deficient heteroaromatic ring and the other have a π-electron rich heteroaromatic ring. A phosphorescent substance such as an iridium-, rhodium-, or platinum-based organometallic complex or a metal complex may be used as one of the combination forming an exciplex. The organic compound described in Embodiment 1 has an electron-transport property and thus can be efficiently used as the first host material. Furthermore, the organic compound has a hole-transport property, and thus can be used as the second host material.
There is no particular limitation on the light-emitting substances that can be used for the light-emitting layers (113, 113a, 113b, and 113c), and a light-emitting substance that converts singlet excitation energy into light in the visible light range or a light-emitting substance that converts triplet excitation energy into light in the visible light range can be used.
<<Light-Emitting Substance that Converts Singlet Excitation Energy into Light>>
The following substances emitting fluorescent light (fluorescent substances) are given as the light-emitting substance that can be used for the light-emitting layers (113, 113a, 113b, and 113c) and convert singlet excitation energy into light emission. The examples include a pyrene derivative, an anthracene derivative, a triphenylene derivative, a fluorene derivative, a carbazole derivative, a dibenzothiophene derivative, a dibenzofuran derivative, a dibenzoquinoxaline derivative, a quinoxaline derivative, a pyridine derivative, a pyrimidine derivative, a phenanthrene derivative, and a naphthalene derivative. A pyrene derivative is particularly preferable because it has a high emission quantum yield. Specific examples of the pyrene derivative include N,N′-bis(3-methylphenyl)-N,N′-bis[3-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6mMemFLPAPrn), N,N′-diphenyl-N,N′-bis[4-(9-phenyl-9H-fluoren-9-yl)phenyl]pyrene-1,6-diamine (abbreviation: 1,6FLPAPrn), N,N′-bis(dibenzofuran-2-yl)-N,N′-diphenylpyrene-1,6-diamine (abbreviation: 1,6FrAPrn), N,N′-bis(dibenzothiophen-2-yl)-N,N′-diphenylpyrene-1,6-diamine (abbreviation: 1,6ThAPrn), N,N′-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-6-amine] (abbreviation: 1,6BnfAPrn), N,N′-(pyrene-1,6-diyl)bis[(N-phenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-02), and N,N′-(pyrene-1,6-diyl)bis[(6,N-diphenylbenzo[b]naphtho[1,2-d]furan)-8-amine] (abbreviation: 1,6BnfAPrn-03).
In addition, it is possible to use 5,6-bis[4-(10-phenyl-9-anthryl)phenyl]-2,2′-bipyridine (abbreviation: PAP2BPy), 5,6-bis[4′-(10-phenyl-9-anthryl)biphenyl-4-yl]-2,2′-bipyridine (abbreviation: PAPP2BPy), N,N′-bis[4-(9H-carbazol-9-yl)phenyl]-N,N′-diphenylstilbene-4,4′-diamine (abbreviation: YGA2S), 4-(9H-carbazol-9-yl)-4′-(10-phenyl-9-anthryl)triphenylamine (abbreviation: YGAPA), 4-(9H-carbazol-9-yl)-4′-(9,10-diphenyl-2-anthryl)triphenylamine (abbreviation: 2YGAPPA), N,9-diphenyl-N-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: PCAPA), 4-(10-phenyl-9-anthryl)-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPA), 4-[4-(10-phenyl-9-anthryl)phenyl]-4′-(9-phenyl-9H-carbazol-3-yl)triphenylamine (abbreviation: PCBAPBA), perylene, 2,5,8,11-tetra-tert-butylperylene (abbreviation: TBP), N,N″-(2-tert-butylanthracene-9,10-diyldi-4,1-phenylene)bis[N,N′,N′-triphenyl-1,4-phenylenediamine] (abbreviation: DPABPA), N,9-diphenyl-N-[4-(9,10-diphenyl-2-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: 2PCAPPA), N-[4-(9,10-diphenyl-2-anthryl)phenyl]-N,N′,N′-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPPA), or the like.
It is also possible to use, for example, N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCABPhA), N-(9,10-diphenyl-2-anthryl)-N,N′,N′-triphenyl-1,4-phenylenediamine (abbreviation: 2DPAPA), N-[9,10-bis(biphenyl-2-yl)-2-anthryl]-N,N′,N′-triphenyl-1,4-phenylenediamine (abbreviation: 2DPABPhA), 9,10-bis(biphenyl-2-yl)-N-[4-(9H-carbazol-9-yl)phenyl]-N-phenylanthracen-2-amine (abbreviation: 2YGABPhA), N,N,9-triphenylanthracen-9-amine (abbreviation: DPhAPhA), coumarin 545T, N,N′-diphenylquinacridone (abbreviation: DPQd), rubrene, 5,12-bis(biphenyl-4-yl)-6,11-diphenyltetracene (abbreviation: BPT), 2-(2-{2-[4-(dimethylamino)phenyl]ethenyl}-6-methyl-4H-pyran-4-ylidene) propanedinitrile (abbreviation: DCM1), 2-{2-methyl-6-[2-(2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCM2), N,N,N′,N′-tetrakis(4-methylphenyl)tetracene-5,11-diamine (abbreviation: p-mPhTD), 7,14-diphenyl-N,N,N′,N′-tetrakis(4-methylphenyl)acenaphtho[1,2-a]fluoranthene-3,10-diamine (abbreviation: p-mPhAFD), 2-{2-isopropyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTI), 2-{2-tert-butyl-6-[2-(1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: DCJTB), 2-(2,6-bis {2-[4-(dimethylamino)phenyl]ethenyl}-4H-pyran-4-ylidene) propanedinitrile (abbreviation: BisDCM), 2-{2,6-bis[2-(8-methoxy-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H-benzo[ij]quinolizin-9-yl) ethenyl]-4H-pyran-4-ylidene}propanedinitrile (abbreviation: BisDCJTM), 1,6BnfAPrn-03, 3,10-bis[N-(9-phenyl-9H-carbazol-2-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10PCA2Nbf (IV)-02), and 3,10-bis[N-(dibenzofuran-3-yl)-N-phenylamino]naphtho[2,3-b;6,7-b′]bisbenzofuran (abbreviation: 3,10FrA2Nbf(IV)-02). In particular, pyrenediamine compounds such as 1,6FLPAPrn, 1,6mMemFLPAPrn, and 1,6BnfAPrn-03 can be used, for example.
<Light-Emitting Substance that Converts Triplet Excitation Energy into Light Emission>>
Next, as examples of the light-emitting substance that converts triplet excitation energy into light emission and can be used for the light-emitting layer 113, a substance that emits phosphorescent light (a phosphorescent substance) and a thermally activated delayed fluorescent (TADF) material that exhibits thermally activated delayed fluorescence are given.
A phosphorescent substance refers to a compound that exhibits phosphorescence but does not exhibit fluorescence at a temperature higher than or equal to low temperatures (e.g., 77 K) and lower than or equal to room temperature (i.e., higher than or equal to 77 K and lower than or equal to 313 K). The phosphorescent substance preferably contains a metal element with large spin-orbit interaction, and can be an organometallic complex, a metal complex (a platinum complex), a rare earth metal complex, or the like. Specifically, a transition metal element is preferable and it is particularly preferable that a platinum group element (ruthenium (Ru), rhodium (Rh), palladium (Pd), osmium (Os), iridium (Ir), or platinum (Pt)), especially iridium, be contained, in which case the transition probability relating to direct transition between the singlet ground state and the triplet excited state can be increased.
<<Phosphorescent Substance (from 450 nm to 570 nm: Blue or Green)>>
As a phosphorescent substance that exhibits blue or green and whose emission spectrum has a peak wavelength at greater than or equal to 450 nm and less than or equal to 570 nm, the following substances are given.
The examples include: organometallic complexes having a 4H-triazole ring, such as tris {2-[5-(2-methylphenyl)-4-(2,6-dimethylphenyl)-4H-1,2,4-triazol-3-yl-κN2]phenyl-κC}iridium(III) (abbreviation: [Ir(mpptz-dmp)3]), tris(5-methyl-3,4-diphenyl-4H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Mptz)3]), tris[4-(3-biphenyl)-5-isopropyl-3-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPrptz-3b)3]), and tris[3-(5-biphenyl)-5-isopropyl-4-phenyl-4H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(iPr5btz)3]); organometallic complexes having a 1H-triazole ring, such as tris[3-methyl-1-(2-methylphenyl)-5-phenyl-1H-1,2,4-triazolato]iridium(III) (abbreviation: [Ir(Mptz1-mp)3]) and tris(1-methyl-5-phenyl-3-propyl-1H-1,2,4-triazolato)iridium(III) (abbreviation: [Ir(Prptz1-Me)3]); organometallic complexes having an imidazole ring, such as fac-tris[1-(2,6-diisopropylphenyl)-2-phenyl-1H-imidazole]iridium(III) (abbreviation: [Ir(iPrpmi)3]) and tris[3-(2,6-dimethylphenyl)-7-methylimidazo[1,2-f]phenanthridinato]iridium(III) (abbreviation: [Ir(dmpimpt-Me)3]); and organometallic complexes in which a ligand is a phenylpyridine derivative having an electron-withdrawing group such as bis[2-(4′,6′-difluorophenyl)pyridinato-N,C2′]iridium(III) tetrakis(1-pyrazolyl) borate (abbreviation: FIr6), bis[2-(4′,6′-difluorophenyl)pyridinato-N,C2′]iridium(III) picolinate (abbreviation: FIrpic), bis {2-[3′,5′-bis(trifluoromethyl)phenyl]pyridinato-N,C2}iridium(III) picolinate (abbreviation: [Ir(CF3ppy)2(pic)]), and bis[2-(4′,6′-difluorophenyl)pyridinato-N,C2′]iridium(III) acetylacetonate (abbreviation: FIr(acac)).
<<Phosphorescent Substance (from 495 nm to 590 nm: Green or Yellow)>>
As a phosphorescent substance that exhibits green or yellow and whose emission spectrum has a peak wavelength at greater than or equal to 495 nm and less than or equal to 590 nm, the following substances are given.
Examples include organometallic iridium complexes including a pyrimidine ring, such as tris(4-methyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)3]), tris(4-t-butyl-6-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)3]), (acetylacetonato)bis(6-methyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(mppm)2(acac)]), (acetylacetonato)bis(6-tert-butyl-4-phenylpyrimidinato)iridium(III) (abbreviation: [Ir(tBuppm)2(acac)]), (acetylacetonato)bis[6-(2-norbornyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(nbppm)2(acac)]), (acetylacetonato)bis[5-methyl-6-(2-methylphenyl)-4-phenylpyrimidinato]iridium(III) (abbreviation: [Ir(mpmppm)2(acac)]), (acetylacetonato)bis {4,6-dimethyl-2-[6-(2,6-dimethylphenyl)-4-pyrimidinyl-κN3]phenyl-κC}iridium(III) (abbreviation: [Ir(dmppm-dmp)2(acac)]), and (acetylacetonato)bis(4,6-diphenylpyrimidinato)iridium(III) (abbreviation: [Ir(dppm)2(acac)]); organometallic iridium complexes including a pyrazine ring, such as (acetylacetonato)bis(3,5-dimethyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-Me)2(acac)]) and (acetylacetonato)bis(5-isopropyl-3-methyl-2-phenylpyrazinato)iridium(III) (abbreviation: [Ir(mppr-iPr)2(acac)]); organometallic iridium complexes including a pyridine ring, such as tris(2-phenylpyridinato-N,C2′)iridium(III) (abbreviation: [Ir(ppy)3]), bis(2-phenylpyridinato-N,C2′)iridium(III) acetylacetonate (abbreviation: [Ir(ppy)2(acac)]), bis(benzo[h]quinolinato)iridium(III) acetylacetonate (abbreviation: [Ir(bzq)2(acac)]), tris(benzo[h]quinolinato)iridium(III) (abbreviation: [Ir(bzq)3]), tris(2-phenylquinolinato-N,C2′)iridium(III) (abbreviation: [Ir(pq)3]), bis(2-phenylquinolinato-N,C2′)iridium(III) acetylacetonate (abbreviation: [Ir(pq)2(acac)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-phenyl-2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: [Ir(ppy)2(4dppy)]), bis[2-(2-pyridinyl-κN)phenyl-κC][2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC], [2-d3-methyl-8-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(5-d3-methyl-2-pyridinyl-κN2)phenyl-κC]iridium(III) (abbreviation: Ir(5mppy-d3)2(mbfpypy-d3)), [2-(methyl-d3)-8-[4-(1-methylethyl-1-d)-2-pyridinyl-κN]benzofuro[2,3-b]pyridin-7-yl-κC]bis[5-(methyl-d3)-2-[5-(methyl-d3)-2-pyridinyl-κN]phenyl-κC]iridium(III) (abbreviation: Ir(5mtpy-d6)2(mbfpypy-iPr-d4)), [2-d3-methyl-(2-pyridinyl-κN)benzofuro[2,3-b]pyridine-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mbfpypy-d3)), and [2-(4-methyl-5-phenyl-2-pyridinyl-κN)phenyl-κC]bis[2-(2-pyridinyl-κN)phenyl-κC]iridium(III) (abbreviation: Ir(ppy)2(mdppy)); organometallic complexes such as bis(2,4-diphenyl-1,3-oxazolato-N,C2′)iridium(III) acetylacetonate (abbreviation: [Ir(dpo)2(acac)]), bis {2-[4′-(perfluorophenyl)phenyl]pyridinato-N,C2′}iridium(III) acetylacetonate (abbreviation: [Ir(p-PF-ph)2(acac)]), and bis(2-phenylbenzothiazolato-N,C2′)iridium(III) acetylacetonate (abbreviation: [Ir(bt)2(acac)]); and a rare earth metal complex such as tris(acetylacetonato) (monophenanthroline) terbium(III) (abbreviation: [Tb(acac)3(Phen)]).
<<Phosphorescent Substance (from 570 nm to 750 nm: Yellow or Red)>>
As a phosphorescent material that exhibits yellow or red and whose emission spectrum has a peak wavelength at greater than or equal to 570 nm and less than or equal to 750 nm, the following substances are given.
The examples include organometallic complexes including a pyrimidine ring, such as (diisobutyrylmethanato)bis[4,6-bis(3-methylphenyl)pyrimidinato]iridium(III) (abbreviation: [Ir(5mdppm)2(dibm)]), bis[4,6-bis(3-methylphenyl)pyrimidinato](dipivaloylmethanato)iridium(III) (abbreviation: [Ir(5mdppm)2(dpm)]), and (dipivaloylmethanato)bis[4,6-di(naphthalen-1-yl)pyrimidinato]iridium(III) (abbreviation: [Ir(d1npm)2(dpm)]); organometallic complexes including a pyrazine ring, such as (acetylacetonato)bis(2,3,5-triphenylpyrazinato)iridium(III) (abbreviation: [Ir(tppr)2(acac)]), bis(2,3,5-triphenylpyrazinato)(dipivaloylmethanato)iridium(III) (abbreviation: [Ir(tppr)2(dpm)]), bis {4,6-dimethyl-2-[3-(3,5-dimethylphenyl)-5-phenyl-2-pyrazinyl-κN]phenyl-κC}(2,6-dimethyl-3,5-heptanedionato-κ2O,O′)iridium(III) (abbreviation: [Ir(dmdppr-P)2(dibm)]), bis {4,6-dimethyl-2-[5-(4-cyano-2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN]phenyl-κC}(2,2,6,6-tetramethyl-3,5-heptanedionato-κ2O,O′)iridium(III) (abbreviation: [Ir(dmdppr-dmCP)2(dpm)]), bis[2-(5-(2,6-dimethylphenyl)-3-(3,5-dimethylphenyl)-2-pyrazinyl-κN)-4,6-dimethylphenyl-κC](2,2′,6,6′-tetramethyl-3,5-heptadionato-κ2O,O′)iridium(III) (abbreviation: [Ir(dmdppr-dmp)2(dpm)]), (acetylacetonato)bis[2-methyl-3-phenylquinoxalinato-N,C2′]iridium(III) (abbreviation: [Ir(mpq)2(acac)]), (acetylacetonato)bis(2,3-diphenylquinoxalinato-N,C2′)iridium(III) (abbreviation: [Ir(dpq)2(acac)]), and (acetylacetonato)bis[2,3-bis(4-fluorophenyl) quinoxalinato]iridium(III) (abbreviation: [Ir(Fdpq)2(acac)]); organometallic complexes including a pyridine ring, such as tris(1-phenylisoquinolinato-N,C2′)iridium(III) (abbreviation: [Ir(piq)3]), bis(1-phenylisoquinolinato-N,C2)iridium(III) acetylacetonate (abbreviation: [Ir(piq)2(acac)]), and bis[4,6-dimethyl-2-(2-quinolinyl-κN)phenyl-κC](2,4-pentanedionato-κ2O,O′)iridium(III) (abbreviation: [Ir(dmpqn)2(acac)]); platinum complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphyrinplatinum(II) (abbreviation: [PtOEP]); and rare earth metal complexes such as tris(1,3-diphenyl-1,3-propanedionato) (monophenanthroline)europium(III) (abbreviation: [Eu(DBM)3(Phen)]) and tris[1-(2-thenoyl)-3,3,3-trifluoroacetonato](monophenanthroline)europium(III) (abbreviation: [Eu(TTA)3(Phen)]).
Any of materials shown below can be used as the TADF material. The TADF material refers to a material that has a small difference (preferably, less than or equal to 0.2 eV) between the S1 level and the T1 level, can up-convert a triplet excited state into a singlet excited state (reverse intersystem crossing) using a little thermal energy, and efficiently exhibits light emission (fluorescence) from the singlet excited state. The thermally activated delayed fluorescence is efficiently obtained under the condition where the difference in energy between the triplet excited energy level and the singlet excited energy level is greater than or equal to 0 eV and less than or equal to 0.2 eV, preferably greater than or equal to 0 eV and less than or equal to 0.1 eV. Delayed fluorescence by the TADF material refers to light emission having a spectrum similar to that of normal fluorescence and an extremely long lifetime. The lifetime is longer than or equal to 1×10−6 seconds, preferably longer than or equal to 1×10−3 seconds. The organic compounds described in Embodiment 1 can also be used.
Note that the TADF material can be also used as an electron-transport material, a hole-transport material, or a host material.
Examples of the TADF material include fullerene, a derivative thereof, an acridine derivative such as proflavine, and eosin. Other examples include a metal-containing porphyrin such as a porphyrin containing magnesium (Mg), zinc (Zn), cadmium (Cd), tin (Sn), platinum (Pt), indium (In), or palladium (Pd). Examples of the metal-containing porphyrin include a protoporphyrin-tin fluoride complex (abbreviation: SnF2(Proto IX)), a mesoporphyrin-tin fluoride complex (abbreviation: SnF2(Meso IX)), a hematoporphyrin-tin fluoride complex (abbreviation: SnF2(Hemato IX)), a coproporphyrin tetramethyl ester-tin fluoride complex (abbreviation: SnF2(Copro III-4Me)), an octaethylporphyrin-tin fluoride complex (abbreviation: SnF2(OEP)), an etioporphyrin-tin fluoride complex (abbreviation: SnF2(Etio I)), and an octaethylporphyrin-platinum chloride complex (abbreviation: PtCl2OEP).
Alternatively, a heteroaromatic compound having a π-electron rich heteroaromatic compound and a π-electron deficient heteroaromatic compound, such as 2-(biphenyl-4-yl)-4,6-bis(12-phenylindolo[2,3-a]carbazol-11-yl)-1,3,5-triazine (abbreviation: PIC-TRZ), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 2-[4-(10H-phenoxazin-10-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: PXZ-TRZ), 3-[4-(5-phenyl-5,10-dihydrophenazin-10-yl)phenyl]-4,5-diphenyl-1,2,4-triazole (abbreviation: PPZ-3TPT), 3-(9,9-dimethyl-9H-acridin-10-yl)-9H-xanthen-9-one (abbreviation: ACRXTN), bis[4-(9,9-dimethyl-9,10-dihydroacridine)phenyl]sulfone (abbreviation: DMAC-DPS), 10-phenyl-10H,10′H-spiro[acridin-9,9′-anthracen]-10′-one (abbreviation: ACRSA), 4-(9′-phenyl-3,3′-bi-9H-carbazol-9-yl)benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzBfpm), 4-[4-(9′-phenyl-3,3′-bi-9H-carbazol-9-yl)phenyl]benzofuro[3,2-d]pyrimidine (abbreviation: 4PCCzPBfpm), and 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), may be used.
Note that a substance in which a π-electron rich heteroaromatic compound is directly bonded to a π-electron deficient heteroaromatic compound is particularly preferable because both the donor property of the π-electron rich heteroaromatic compound and the acceptor property of the π-electron deficient heteroaromatic compound are improved and the energy difference between the singlet excited state and the triplet excited state becomes small. As the TADF material, a TADF material (TADF 100) in which a singlet excited state and a triplet excited state are in a thermal equilibrium state may be used. Since such a TADF material enables a short emission lifetime (excitation lifetime), an efficiency decrease of a light-emitting device in a high-luminance region can be inhibited.
As the material having a function of converting triplet excitation energy into light emission, a nanostructure of a transition metal compound having a perovskite structure is also given in addition to the above. In particular, a nanostructure of a metal-halide perovskite material is preferable. The nanostructure is preferably a nanoparticle or a nanorod.
As the organic compounds (the host material and the like) used in combination with the above-described light-emitting substance (the guest material) in the light-emitting layers (113, 113a, 113b, and 113c), one or more kinds of substances having a larger energy gap than the light-emitting substance (the guest material) may be selected to be used.
In the case where the light-emitting substance used in the light-emitting layers (113, 113a, 113b, and 113c) is a fluorescent substance, an organic compound (a host material) used in combination with the light-emitting substance is preferably an organic compound having a high energy level in a singlet excited state and a low energy level in a triplet excited state or an organic compound having a high fluorescence quantum yield. Therefore, the hole-transport material (described above) or the electron-transport material (described below) shown in this embodiment, for example, can be used as long as they are organic compounds that satisfy such a condition. The organic compounds described in Embodiment 1 can also be used.
In terms of a preferable combination with the light-emitting substance (the fluorescent substance), examples of the organic compound (the host material) include condensed polycyclic aromatic compounds such as an anthracene derivative, a tetracene derivative, a phenanthrene derivative, a pyrene derivative, a chrysene derivative, and a dibenzo[g,p]chrysene derivative, although some of them overlap with the above specific examples.
Note that specific examples of the organic compound (the host material) preferably used in combination with the fluorescent substance include 9-phenyl-3-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: PCzPA), 3,6-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazole (abbreviation: DPCzPA), 3-[4-(1-naphthyl)-phenyl]-9-phenyl-9H-carbazole (abbreviation: PCPN), 9,10-diphenylanthracene (abbreviation: DPAnth), N,N-diphenyl-9-[4-(10-phenyl-9-anthryl)phenyl]-9H-carbazol-3-amine (abbreviation: CzA1PA), 4-(10-phenyl-9-anthryl)triphenylamine (abbreviation: DPhPA), YGAPA, PCAPA, N,9-diphenyl-N-{4-[4-(10-phenyl-9-anthryl)phenyl]phenyl}-9H-carbazol-3-amine (abbreviation: PCAPBA), N-(9,10-diphenyl-2-anthryl)-N,9-diphenyl-9H-carbazol-3-amine (abbreviation: 2PCAPA), 6,12-dimethoxy-5,11-diphenylchrysene, N,N,N′,N′,N″,N″,N′″,N′″-octaphenyldibenzo[g,p]chrysene-2,7,10,15-tetraamine (abbreviation: DBC1), 9-[4-(10-phenyl-9-anthracenyl)phenyl]-9H-carbazole (abbreviation: CzPA), 7-[4-(10-phenyl-9-anthryl)phenyl]-7H-dibenzo[c,g]carbazole (abbreviation: cgDBCzPA), 6-[3-(9,10-diphenyl-2-anthryl)phenyl]-benzo[b]naphtho[1,2-d]furan (abbreviation: 2mBnfPPA), 9-phenyl-10-{4-(9-phenyl-9H-fluoren-9-yl)-biphenyl-4′-yl}-anthracene (abbreviation: FLPPA), 9,10-bis(3,5-diphenylphenyl) anthracene (abbreviation: DPPA), 9,10-di(2-naphthyl) anthracene (abbreviation: DNA), 2-tert-butyl-9,10-di(2-naphthyl) anthracene (abbreviation: t-BuDNA), 9-(1-naphthyl)-10-(2-naphthyl) anthracene (abbreviation: α,β-ADN), 2-(10-phenylanthracen-9-yl)dibenzofuran, 2-(10-phenyl-9-anthracenyl)-benzo[b]naphtho[2,3-d]furan (abbreviation: Bnf(II)PhA), 9-(1-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: αN-βNP Anth), 2,9-di(1-naphthyl)-10-phenylanthracene (abbreviation: 2αN-αNPhA), 9-(1-naphthyl)-10-[3-(1-naphthyl)phenyl]anthracene (abbreviation: αN-mαNPAnth), 9-(2-naphthyl)-10-[3-(1-naphthyl)phenyl]anthracene (abbreviation: βN-mαNPAnth), 9-(1-naphthyl)-10-[4-(1-naphthyl)phenyl]anthracene (abbreviation: αN-αNPAnth), 9-(2-naphthyl)-10-[4-(2-naphthyl)phenyl]anthracene (abbreviation: βN-βNPAnth), 2-(1-naphthyl)-9-(2-naphthyl)-(10-phanylanthracene (abbreviation: 2αN-βNPhA), 9-(2-naphthyl)-10-[3-(2-naphthyl)phenyl]anthracene (abbreviation: βN-mβNPAnth), 1-[4-(10-(biphenyl-4-yl)-9-anthracenyl)phenyl]-2-ethyl-1H-benzimidazole (abbreviation: EtBImPBPhA), 9,9′-bianthryl (abbreviation: BANT), 9,9′-(stilbene-3,3′-diyl)diphenanthrene (abbreviation: DPNS), 9,9′-(stilbene-4,4′-diyl)diphenanthrene (abbreviation: DPNS2), 1,3,5-tri (1-pyrenyl)benzene (abbreviation: TPB3), 5,12-diphenyltetracene, and 5,12-bis(biphenyl-2-yl)tetracene.
In the case where the light-emitting substance used for the light-emitting layers (113, 113a, 113b, and 113c) is a phosphorescent substance, an organic compound having triplet excitation energy (energy difference between a ground state and a triplet excited state) which is higher than triplet excitation energy of the light-emitting substance is preferably selected as the organic compound (the host material) used in combination with the light-emitting substance. Note that in the case where a plurality of organic compounds (e.g., the first host material and the second host material (or an assist material)) are used in combination with a light-emitting substance in order to form an exciplex, the plurality of organic compounds are preferably mixed with a phosphorescent substance. The organic compounds described in Embodiment 1 can also be used.
Such a structure makes it possible to efficiently obtain light emission utilizing ExTET (Exciplex-Triplet Energy Transfer), which is energy transfer from an exciplex to a light-emitting substance. Note that a combination of the plurality of organic compounds that easily forms an exciplex is preferably employed, and it is particularly preferable to combine a compound that easily accepts holes (a hole-transport material) and a compound that easily accepts electrons (an electron-transport material).
In terms of a preferable combination with the light-emitting substance (phosphorescent substance), examples of the organic compounds (the host material and the assist material) include an aromatic amine (an organic compound having an aromatic amine skeleton), a carbazole derivative (an organic compound having a carbazole ring), a dibenzothiophene derivative (an organic compound having a dibenzothiophene ring), a dibenzofuran derivative (an organic compound having a dibenzofuran ring), an oxadiazole derivative (an organic compound having an oxadiazole ring), a triazole derivative (an organic compound having a triazole ring), a benzimidazole derivative (an organic compound having a benzimidazole ring), a quinoxaline derivative (an organic compound having a quinoxaline ring), a dibenzoquinoxaline derivative (an organic compound having a dibenzoquinoxaline ring), a pyrimidine derivative (an organic compound having a pyrimidine ring), a triazine derivative (an organic compound having a triazine ring), a pyridine derivative (an organic compound having a pyridine ring), a bipyridine derivative (an organic compound having a bipyridine ring), a phenanthroline derivative (an organic compound having a phenanthroline ring), a furodiazine derivative (an organic compound having a furodiazine ring), and zinc- and aluminum-based metal complexes, although some of them overlap with the above specific examples.
Among the above organic compounds, specific examples of the aromatic amine and the carbazole derivative, which are organic compounds having a high hole-transport property, are the same as the specific examples of the hole-transport materials described above. Any of these is preferable as the host material.
Among the above organic compounds, specific examples of the dibenzothiophene derivative and the dibenzofuran derivative, which are organic compounds having a high hole-transport property, include 4-{3-[3-(9-phenyl-9H-fluoren-9-yl)phenyl]phenyl}dibenzofuran (abbreviation: mmDBFFLBi-II), 4,4′,4″-(benzene-1,3,5-triyl)tri (dibenzofuran) (abbreviation: DBF3P-II), DBT3P-II, 2,8-diphenyl-4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]dibenzothiophene (abbreviation: DBTFLP-III), 4-[4-(9-phenyl-9H-fluoren-9-yl)phenyl]-6-phenyldibenzothiophene (abbreviation: DBTFLP-IV), and 4-[3-(triphenylen-2-yl)phenyl]dibenzothiophene (abbreviation: mDBTPTp-II). Any of these is preferable as the host material.
In addition, a metal complex having an oxazole-based or thiazole-based ligand, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ), or the like is given as a preferable example of the host material.
Among the above organic compounds, specific examples of the oxadiazole derivative, the triazole derivative, the benzimidazole derivative, the quinoxaline derivative, the dibenzoquinoxaline derivative, the quinazoline derivative, the phenanthroline derivative, and the like, which are organic compounds having a high electron-transport property, include an organic compound including a heteroaromatic ring having a polyazole ring, such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4′-bis(5-methylbenzoxazol-2-yl) stilbene (abbreviation: BzOs); an organic compound including a heteroaromatic ring having a pyridine ring, such as bathophenanthroline (abbreviation: Bphen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2′-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), and 2,2′-(1,1′-biphenyl)-4,4′-diylbis(9-phenyl-1,10-phenanthroline) (abbreviation: PPhen2BP); 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), 2-{4-[9,10-di(2-naphthyl)-2-anthryl]phenyl}-1-phenyl-1H-benzimidazole (abbreviation: ZADN), and 2-[4′-(9-phenyl-9H-carbazol-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq). Any of these is preferable as the host material.
Among the above organic compounds, specific examples of the pyridine derivative, the diazine derivative (including the pyrimidine derivative, the pyrazine derivative, and the pyridazine derivative), the triazine derivative, and the furodiazine derivative, which are organic compounds having a high electron-transport property, include organic compounds including a heteroaromatic ring having a diazine ring, such as 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy), 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), 9,9′-[pyrimidine-4,6-diylbis(biphenyl-3,3′-diyl)]bis(9H-carbazole) (abbreviation: 4,6mCzBP2Pm), 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), 8-(biphenyl-4-yl)-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8BP-4mDBtPBfpm), 9-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr), 9-[3′-(dibenzothiophen-4-yl)biphenyl-4-yl]naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9pmDBtBPNfpr), 11-[3′-dibenzothiophen-4-yl)bipheny-3-yl]phenanthro[9′,10′: 4,5]furo[2,3-b]pyrazine (abbreviation: 11mDBtBPPnfpr), 11-[3′-(dibenzothiophen-4-yl)biphenyl-4-yl]phenanthro[9′,10′: 4,5]furo[2,3-b]pyrazine, 11-[(3′-(9H-carbazol-9-yl)biphenyl-3-yl]phenanthro[9′,10′: 4,5]furo[2,3-b]pyrazine, 12-(9′-phenyl-3,3′-bi-9H-carbazol-9-yl) phenanthro[9′,10′: 4,5]furo[2,3-b]pyrazine (abbreviation: 12PCCzPnfpr), 9-[(3′-9-phenyl-9H-carbazol-3-yl)biphenyl-4-yl]naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9pmPCBPNfpr), 9-(9′-phenyl-3,3′-bi-9H-carbazol-9-yl) naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9PCCzNfpr), 10-(9′-phenyl-3,3′-bi-9H-carbazol-9-yl) naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 10PCCzNfpr), 9-[3′-(6-phenylbenzo[b]naphtho[1,2-d]furan-8-yl)biphenyl-3-yl]naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9mBnfBPNfpr), 9-{3-[6-(9,9-dimethylfluoren-2-yl)dibenzothiophen-4-yl]phenyl}naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9mFDBtPNfpr), 9-[3′-(6-phenyldibenzothiophen-4-yl)biphenyl-3-yl]naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9mDBtBPNfpr-02), 9-[3-(9′-phenyl-3,3′-bi-9H-carbazol-9-yl)phenyl]naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine (abbreviation: 9mPCCzPNfpr), 9-{(3′-[2,8-diphenyldibenzothiophen-4-yl)biphenyl-3-yl}naphtho[1′,2′: 4,5]furo[2,3-b]pyrazine, 11-{(3′-[2,8-diphenyldibenzothiophen-4-yl)biphenyl-3-yl]phenanthro[9′,10′: 4,5]furo[2,3-b]pyrazine, 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3′-(triphenylen-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 2-(biphenyl-4-yl)-4-phenyl-6-[9,9′-spirobi (9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-calbazole (abbreviation: PCzDBfTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-(8-[(1, l′: 4′,1″-terphenyl)-4-yl-1-dibenzofuranyl]-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), and 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm). Any of these are preferable as the host material.
Among the above organic compounds, specific examples of metal complexes that are organic compounds having a high electron-transport property include zinc- and aluminum-based metal complexes, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq), tris(4-methyl-8-quinolinolato)aluminum(III) (abbreviation: Almq3), bis(10-hydroxybenzo[h]quinolinato) beryllium(II) (abbreviation: BeBq2), bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), and bis(8-quinolinolato)zinc(II) (abbreviation: Znq), and metal complexes having a quinoline ring or a benzoquinoline ring. Any of these are preferable as the host material.
In addition, a high molecular compound such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy) is also preferable as the host material.
It is also possible to use an organic compound having a bipolar property, i.e., both a high hole-transport property and a high electron-transport property, and including a diazine ring, such as 9-phenyl-9′-(4-phenyl-2-quinazolinyl)-3,3′-bi-9H-carbazole (abbreviation: PCCzQz), 2-[4′-(9-phenyl-9H-carbazol-3-yl)-3,1′-biphenyl-1-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mpPCBPDBq), 5-[3-(4,6-diphenyl-1,3,5-triazin-2yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 11-[4-(biphenyl-4-yl)-6-phenyl-1,3,5-triazin-2-yl]-11,12-dihydro-12-phenyl-indolo[2,3-a]carbazole (abbreviation: BP-Icz(II)Tzn), or 7-[4-(9-phenyl-9H-carbazol-2-yl) quinazolin-2-yl]-7H-dibenzo[c,g]carbazole (abbreviation: PC-cgDBCzQz) can be used as the host material.
The electron-transport layers (114, 114a, and 114b) are layers transporting the electrons, which are injected from the second electrode 102 and the charge-generation layers (106, 106a, and 106b) by electron-injection layers (115, 115a, and 115b) described later, to the light-emitting layers (113, 113a, 113b, and 113c). The light-emitting device of one embodiment of the present invention can have improved heat resistance when the electron-transport layer has a stacked-layer structure. The electron-transport materials used for the electron-transport layers (114, 114a, and 114b) are preferably substances with an electron mobility higher than or equal to 1×10−6 cm2/Vs in the case where the square root of the electric field strength [V/cm] is 600. Note that any other substance can be used as long as the substance has an electron-transport property higher than a hole-transport property. Each of the electron-transport layers (114, 114a, and 114b) functions even in the form of a single layer but may have a stacked-layer structure of two or more layers. Note that since the above-described mixed material has heat resistance, performing a photolithography step over the electron-transport layer including such a material can inhibit the influence of a thermal process on the device characteristics.
As the electron-transport material that can be used for the electron-transport layers (114, 114a, and 114b), an organic compound with a high electron-transport property can be used; for example, a heteroaromatic compound can be used. Note that the heteroaromatic compound refers to a cyclic compound containing at least two different kinds of elements in a ring. Examples of a cyclic structure include a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, and the like, among which a five-membered ring and a six-membered ring are particularly preferable; the elements contained in the heteroaromatic compound are preferably one or more of nitrogen, oxygen, sulfur, and the like, as well as carbon. In particular, a heteroaromatic compound containing nitrogen (a nitrogen-containing heteroaromatic compound) is preferable, and any of materials having a high electron-transport property (electron-transport materials), such as a nitrogen-containing heteroaromatic compound and a π-electron deficient heteroaromatic compound including the nitrogen-containing heteroaromatic compound, is preferably used. The compound in Embodiment 1 has an electron-transport property and thus can be used as an electron-transport material. It is further preferable that the compound of the present application be used for both the electron-transport layer 114a and the electron-transport layer 114b.
Note that a material different from a material used for the light-emitting layer can be used as the electron-transport material. Not all excitons formed by recombination of carriers in the light-emitting layer can contribute to light emission and some excitons are diffused into a layer in contact with or in the vicinity of the light-emitting layer. In order to avoid this phenomenon, the energy level (the lowest singlet excitation energy level or the lowest triplet excitation energy level) of a material used for the layer in contact with or in the vicinity of the light-emitting layer is preferably higher than that of a material used for the light-emitting layer. Therefore, when a material different from a material used for the light-emitting layer is used as the electron-transport material, a light-emitting device with high efficiency can be obtained.
The heteroaromatic compound is an organic compound including at least one heteroaromatic ring.
Note that the heteroaromatic ring has any one of a pyridine ring, a diazine ring, a triazine ring, a polyazole ring, an oxazole ring, a thiazole ring, and the like. A heteroaromatic ring having a diazine ring includes a heteroaromatic ring having a pyrimidine ring, a pyrazine ring, a pyridazine ring, or the like. A heteroaromatic ring having a polyazole ring includes a heteroaromatic ring having an imidazole ring, a triazole ring, or an oxadiazole ring.
The heteroaromatic ring includes a condensed heteroaromatic ring having a fused ring structure. Examples of the condensed heteroaromatic ring include a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a quinazoline ring, a benzoquinazoline ring, a dibenzoquinazoline ring, a phenanthroline ring, a furodiazine ring, and a benzimidazole ring.
Examples of a heteroaromatic compound containing carbon and one or more of nitrogen, oxygen, sulfur, and the like and having a five-membered ring structure include a heteroaromatic compound having an imidazole ring, a heteroaromatic compound having a triazole ring, a heteroaromatic compound having an oxazole ring, a heteroaromatic compound having an oxadiazole ring, a heteroaromatic compound having a thiazole ring, and a heteroaromatic compound having a benzimidazole ring.
Examples of a heteroaromatic compound containing carbon and one or more of nitrogen, oxygen, sulfur, and the like and having a six-membered ring structure include a heteroaromatic compound having a heteroaromatic ring such as a pyridine ring, a diazine ring (including a pyrimidine ring, a pyrazine ring, a pyridazine ring, or the like), a triazine ring, or a polyazole ring.
Other examples include a heteroaromatic compound having a bipyridine structure and a heteroaromatic compound having a terpyridine structure, which are included in heteroaromatic compounds in which pyridine rings are connected.
Examples of the heteroaromatic compound with a fused ring structure which partly has the above six-membered ring structure include a heteroaromatic compound having a condensed heteroaromatic ring such as a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, a phenanthroline ring, a furodiazine ring (including a structure where an aromatic ring is fused to the furan ring of a furodiazine ring), or a benzimidazole ring.
Specific examples of the above-described heteroaromatic compound having a five-membered ring structure (e.g., a polyazole ring (including an imidazole ring, a triazole ring, or an oxadiazole ring), an oxazole ring, a thiazole ring, or a benzimidazole ring) include 2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (abbreviation: PBD), 1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene (abbreviation: OXD-7), 9-[4-(5-phenyl-1,3,4-oxadiazol-2-yl)phenyl]-9H-carbazole (abbreviation: CO11), 3-(4-biphenylyl)-4-phenyl-5-(4-tert-butylphenyl)-1,2,4-triazole (abbreviation: TAZ), 3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole (abbreviation: p-EtTAZ), 2,2′,2″-(1,3,5-benzenetriyl)tris(1-phenyl-1H-benzimidazole) (abbreviation: TPBI), 2-[3-(dibenzothiophen-4-yl)phenyl]-1-phenyl-1H-benzimidazole (abbreviation: mDBTBIm-II), and 4,4′-bis(5-methylbenzoxazol-2-yl) stilbene (abbreviation: BzOs).
Specific examples of the above-described heteroaromatic compound having a six-membered ring structure (including a heteroaromatic ring having a pyridine ring, a diazine ring, a triazine ring, or the like) include a heteroaromatic compound including a heteroaromatic ring having a pyridine ring, such as 3,5-bis[3-(9H-carbazol-9-yl)phenyl]pyridine (abbreviation: 35DCzPPy) or 1,3,5-tri[3-(3-pyridyl)phenyl]benzene (abbreviation: TmPyPB), a heteroaromatic compound including a heteroaromatic ring having a triazine ring, such as 2-{4-[3-(N-phenyl-9H-carbazol-3-yl)-9H-carbazol-9-yl]phenyl}-4,6-diphenyl-1,3,5-triazine (abbreviation: PCCzPTzn), 9-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-9′-phenyl-2,3′-bi-9H-carbazole (abbreviation: mPCCzPTzn-02), 5-[3-(4,6-diphenyl-1,3,5-triazin-2-yl)phenyl]-7,7-dimethyl-5H,7H-indeno[2,1-b]carbazole (abbreviation: mINc(II)PTzn), 2-[3′-(triphenylen-2-yl)-1,1′-biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mTpBPTzn), 2-[(1,1′-biphenyl)-4-yl]-4-phenyl-6-[9,9′-spirobi (9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), 2,6-bis(4-naphthalen-1-ylphenyl)-4-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), 9-[4-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzothienyl]-2-phenyl-9H-carbazole (abbreviation: PCzDBfTzn), 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), 2-(biphenyl-3-yl)-4-phenyl-6-(8-[1,1′: 4′,1″-terphenyl]-4-yl-1-dibenzofuranyl)-1,3,5-triazine (abbreviation: mBP-TPDBfTzn), or 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), and a heteroaromatic compound including a heteroaromatic ring having a diazine (pyrimidine) ring, such as 4,6-bis[3-(phenanthren-9-yl)phenyl]pyrimidine (abbreviation: 4,6mPnP2Pm), 4,6-bis[3-(4-dibenzothienyl)phenyl]pyrimidine (abbreviation: 4,6mDBTP2Pm-II), 4,6-bis[3-(9H-carbazol-9-yl)phenyl]pyrimidine (abbreviation: 4,6mCzP2Pm), 4,6mCzBP2Pm, 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1′-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4-[3-(dibenzothiophen-4-yl)phenyl]-8-(naphthalen-2-yl)-[1]benzofuro[3,2-4Cz2PPm), d]pyrimidine (abbreviation: 8βN-4mDBtPBfpm), 8BP-4mDBtPBfpm, 9mDBtBPNfpr, 9pmDBtBPNfpr, 3,8-bis[3-(dibenzothiophen-4-yl)phenyl]benzofuro[2,3-b]pyrazine (abbreviation: 3,8mDBtP2Bfpr), 4,8-bis[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 4,8mDBtP2Bfpm), 8-[3′-(dibenzothiophen-4-yl)(biphenyl-3-yl)]naphtho[1′,2′: 4,5]furo[3,2-d]pyrimidine (abbreviation: 8mDBtBPNfpm), or 8-[(2,2′-binaphthalen)-6-yl]-4-[3-(dibenzothiophen-4-yl)phenyl]-[1]benzofuro[3,2-d]pyrimidine (abbreviation: 8(βN2)-4mDBtPBfpm). Note that the above aromatic compounds including a heteroaromatic ring include a heteroaromatic compound having a condensed heteroaromatic ring.
Other examples include a heteroaromatic compound including a heteroaromatic ring having a diazine (pyrimidine) ring, such as 2,2′-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2,2′-(2,2′-bipyridine-6,6′-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 6,6′(P-Bqn)2BPy), 2,2′-(pyridine-2,6-diyl)bis {4-[4-(2-naphthyl)phenyl]-6-phenylpyrimidine} (abbreviation: 2,6(NP-PPm)2Py), or 6-(biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), and a heteroaromatic compound including a heteroaromatic ring having a triazine ring, such as 2,4,6-tris(3′-(pyridin-3-yl)biphenyl-3-yl)-1,3,5-triazine (abbreviation: TmPPPyTz), 2,4,6-tris(2-pyridyl)-1,3,5-triazine (abbreviation: 2Py3Tz), or 2-[3-(2,6-dimethyl-3-pyridyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn).
Specific examples of the above-described heteroaromatic compound with a fused ring structure which partly has the six-membered ring structure (a heteroaromatic compound having a fused ring structure) include a heteroaromatic compound having a quinoxaline ring, such as bathophenanthroline (abbreviation: BPhen), bathocuproine (abbreviation: BCP), 2,9-di(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline (abbreviation: NBphen), 2,2′-(1,3-phenylene)bis(9-phenyl-1,10-phenanthroline) (abbreviation: mPPhen2P), 2,2′-(1,1′-biphenyl)-4,4′-diylbis(9-phenyl-1,10-phenanthroline) (abbreviation: PPhen2BP), 2,2′-(pyridine-2,6-diyl)bis(4-phenylbenzo[h]quinazoline) (abbreviation: 2,6(P-Bqn)2Py), 2-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTPDBq-II), 2-[3′-(dibenzothiophen-4-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mDBTBPDBq-II), 2-[3′-(9H-carbazol-9-yl)biphenyl-3-yl]dibenzo[f,h]quinoxaline (abbreviation: 2mCzBPDBq), 2-[4-(3,6-diphenyl-9H-carbazol-9-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 2CzPDBq-III), 7-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 7mDBTPDBq-II), 6-[3-(dibenzothiophen-4-yl)phenyl]dibenzo[f,h]quinoxaline (abbreviation: 6mDBTPDBq-II), or 2mpPCBPDBq.
For the electron-transport layers (114, 114a, and 114b), any of the metal complexes given below as well as the heteroaromatic compounds given above can be used. Examples of the metal complexes include a metal complex including a quinoline ring or a benzoquinoline ring, such as tris(8-quinolinolato)aluminum(III) (abbreviation: Alq3), Almq3, 8-quinolinolatolithium(I) (abbreviation: Liq), BeBq2, bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum(III) (abbreviation: BAlq), or bis(8-quinolinolato)zinc(II) (abbreviation: Znq), and a metal complex including an oxazole ring or a thiazole ring, such as bis[2-(2-benzoxazolyl)phenolato]zinc(II) (abbreviation: ZnPBO) or bis[2-(2-benzothiazolyl)phenolato]zinc(II) (abbreviation: ZnBTZ).
A high molecular compound such as poly(2,5-pyridinediyl) (abbreviation: PPy), poly[(9,9-dihexylfluorene-2,7-diyl)-co-(pyridine-3,5-diyl)] (abbreviation: PF-Py), or poly[(9,9-dioctylfluorene-2,7-diyl)-co-(2,2′-bipyridine-6,6′-diyl)] (abbreviation: PF-BPy) can also be used as an electron-transport material.
Each of the electron-transport layers (114, 114a, and 114b) is not limited to a single layer, and may be a stack of two or more layers each made of any of the above substances.
The electron-injection layers (115, 115a, and 115b) are each a layer containing a substance having a high electron-injection property. The electron-injection layers (115, 115a, and 115b) are each a layer for increasing the efficiency of electron injection from the second electrode 102 and are each preferably formed using a material whose LUMO level value has a small difference (0.5 eV or less) from the work function value of the material used for the second electrode 102. Thus, the electron-injection layer 115 can be formed using an alkali metal, an alkaline earth metal, or a compound thereof, such as lithium, cesium, lithium fluoride (LiF), cesium fluoride (CsF), calcium fluoride (CaF2), Liq, 2-(2-pyridyl)phenolatolithium (abbreviation: LiPP), 2-(2-pyridyl)-3-pyridinolatolithium (abbreviation: LiPPy), 4-phenyl-2-(2-pyridyl)phenolatolithium (abbreviation: LiPPP), lithium oxide (LiOx), or cesium carbonate. A rare earth metal or a rare earth metal compound, such as erbium fluoride (ErF3) or ytterbium (Yb), can also be used. Note that to form the electron-injection layers (115, 115a, and 115b), a plurality of kinds of the above-described materials may be mixed or a plurality of kinds of the above-described materials may be stacked. Electride may also be used for the electron-injection layers (115, 115a, and 115b). Examples of the electride include a substance in which electrons are added at high concentration to calcium oxide-aluminum oxide. Note that any of the above-described substances contained in the electron-transport layers (114, 114a, and 114b) can also be used. The compound of the present application has an excellent electron-transport property, and thus is suitably used for an electron-injection layer. It is further preferable that the compound of the present application be used for both the electron-injection layer 115a and the electron-injection layer 115b.
A mixed material in which an organic compound and an electron donor (donor) are mixed may also be used for the electron-injection layers (115, 115a, and 115b). Such a mixed material is excellent in an electron-injection property and an electron-transport property because electrons are generated in the organic compound by the electron donor. In this case, the organic compound is preferably a material excellent in transporting the generated electrons; specifically, for example, the above-described electron-transport materials (e.g., metal complexes and heteroaromatic compounds) used in the electron-transport layers (114, 114a, and 114b) can be used. Any substance showing an electron-donating property with respect to the organic compound can serve as an electron donor. Specifically, an alkali metal, an alkaline earth metal, and a rare earth metal are preferable, and lithium, cesium, magnesium, calcium, erbium, ytterbium, and the like are given as examples. In addition, an alkali metal oxide and an alkaline earth metal oxide are preferable, and lithium oxide, calcium oxide, barium oxide, and the like are given as examples. A Lewis base such as magnesium oxide can also be used. An organic compound such as tetrathiafulvalene (abbreviation: TTF) can also be used. Alternatively, a stack of these materials may be used.
Moreover, a mixed material in which an organic compound and a metal are mixed may also be used for the electron-injection layers (115, 115a, and 115b). The organic compound used here preferably has a LUMO level higher than or equal to −3.6 eV and lower than or equal to −2.3 eV. Moreover, a material having an unshared electron pair is preferable.
Thus, as the organic compound used in the above mixed material, a mixed material obtained by mixing a metal and the heteroaromatic compound given above as the material that can be used for the electron-transport layer may be used. Preferable examples of the heteroaromatic compound include materials having an unshared electron pair, such as a heteroaromatic compound having a five-membered ring structure (e.g., an imidazole ring, a triazole ring, an oxazole ring, an oxadiazole ring, a thiazole ring, or a benzimidazole ring), a heteroaromatic compound having a six-membered ring structure (e.g., a pyridine ring, a diazine ring (including a pyrimidine ring, a pyrazine ring, a pyridazine ring, and the like), a triazine ring, a bipyridine ring, or a terpyridine ring), and a heteroaromatic compound with a fused ring structure which partly has a six-membered ring structure (e.g., a quinoline ring, a benzoquinoline ring, a quinoxaline ring, a dibenzoquinoxaline ring, or a phenanthroline ring). Since the materials are specifically described above, description thereof is omitted here.
As the metal used for the above mixed material, a transition metal belonging to Group 5, Group 7, Group 9, or Group 11 in the periodic table or a material belonging to Group 13 is preferably used, and Ag, Cu, Al, In, and the like can be given as examples. Here, the organic compound forms a singly occupied molecular orbital (SOMO) with the transition metal.
To amplify light obtained from the light-emitting layer 113b, for example, the optical path length between the second electrode 102 and the light-emitting layer 113b is preferably less than one-fourth of the wavelength λ of light emitted from the light-emitting layer 113b. In that case, the optical path length can be adjusted by changing the thickness of the electron-transport layer 114b or the electron-injection layer 115b.
When the charge-generation layer 106 is provided between two EL layers (103a and 103b) as in the light-emitting device illustrated in
The charge-generation layer 106 has a function of injecting electrons into the EL layer 103a and injecting holes into the EL layer 103b when a voltage is applied between the first electrode (anode) 101 and the second electrode (cathode) 102. The charge-generation layer 106 may have either a structure where an electron acceptor (acceptor) is added to a hole-transport material (also referred to as a P-type layer) or a structure where an electron donor (donor) is added to an electron-transport material (also referred to as an electron-injection buffer layer). Alternatively, both of these structures may be stacked. Furthermore, an electron-relay layer may be provided between the P-type layer and the electron-injection buffer layer. Note that forming the charge-generation layer 106 with the use of any of the above materials can inhibit an increase in driving voltage caused by the stack of the EL layers. The compound of the present application has an excellent transport property, and thus is suitably used for the charge-generation layer 106.
In the case where the charge-generation layer 106 has a structure where an electron acceptor is added to a hole-transport material that is an organic compound (a P-type layer), any of the materials described in this embodiment can be used as the hole-transport material. As examples of the electron acceptor, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane (abbreviation: F4-TCNQ), chloranil, and the like can be given. Other examples include oxides of metals belonging to Group 4 to Group 8 in the periodic table. Specific examples include vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, manganese oxide, and rhenium oxide. Any of the above-described acceptor materials may be used. Furthermore, a mixed film obtained by mixing materials of the P-type layer or a stack of single films containing the respective materials may be used.
In the case where the charge-generation layer 106 has a structure where an electron donor is added to an electron-transport material (an electron-injection buffer layer), any of the materials described in this embodiment can be used as the electron-transport material. As the electron donor, it is possible to use an alkali metal, an alkaline earth metal, a rare earth metal, a metal belonging to Group 2 or Group 13 in the periodic table, or an oxide or a carbonate thereof. Specifically, lithium (Li), cesium (Cs), magnesium (Mg), calcium (Ca), ytterbium (Yb), indium (In), lithium oxide (Li2O), cesium carbonate, or the like is preferably used. An organic compound such as tetrathianaphthacene may be used as the electron donor.
When an electron-relay layer is provided between a P-type layer and an electron-injection buffer layer in the charge-generation layer 106, the electron-relay layer contains at least a substance having an electron-transport property and has a function of preventing an interaction between the electron-injection buffer layer and the P-type layer and transferring electrons smoothly. The LUMO level of the substance having an electron-transport property in the electron-relay layer is preferably between the LUMO level of the acceptor substance in the P-type layer and the LUMO level of the substance having an electron-transport property in the electron-transport layer in contact with the charge-generation layer 106. A specific energy level of the LUMO level of the substance having an electron-transport property which is used for the electron-relay layer is preferably higher than or equal to −5.0 eV, further preferably higher than or equal to −5.0 eV and lower than or equal to −3.0 eV. Note that as the substance having an electron-transport property in the electron-relay layer, a phthalocyanine-based material or a metal complex having a metal-oxygen bond and an aromatic ligand is preferably used.
Although
Although not illustrated in
In a bendable device (also referred to as flexible device) that uses a flexible substrate as a substrate, a bent portion might be decreased in light extraction efficiency or might be decreased in emission efficiency due to influence of external light or the like. Thus, a material with a high refractive index is preferably used for a cap layer in the bent portion. More specifically, a cap layer, a cathode, a layer including the compound of the present application, and a light-emitting layer are preferably placed to overlap with each other in the bent portion. In that case, the refractive index of the compound of the present application is preferably lower than the refractive index of the cap layer material and the refractive index of the host material in the light-emitting layer. In a device including a plurality of bent portions or in a wind-up device, many bent portions are included; thus, a cap layer, a layer including the compound of the present application, and a light-emitting layer are preferably provided to overlap with each other in each of the bent portions.
The LUMO level of the electron-transport layer material is lower than the LUMO level of the cap layer material preferably by 0.3 eV or more, further preferably by 0.5 eV or more. The LUMO level of the host material in the light-emitting layer is higher than the LUMO level of the cap layer material preferably by 0.1 eV or more, further preferably by 0.3 eV or more. It is particularly preferable that the LUMO levels satisfy the relation of the cap layer material >the host material in the light-emitting layer >the electron-transport layer material. In the case where a plurality of light-emitting devices (e.g., a red device, a blue device, and a green device) are included, each of the light-emitting devices preferably satisfies the relation of the LUMO levels.
Specific examples of a material that can be used for the cap layer include 5,5′-diphenyl-2,2′-di-5H-[1]benzothieno[3,2-c]carbazole (abbreviation: BisBTc) and 4,4′,4″-(benzene-1,3,5-triyl)tri (dibenzothiophene) (abbreviation: DBT3P-II). A compound having a triarylamine skeleton is preferable because of its stability. In view of the stability, it is effective to use a compound having a triarylamine skeleton for both the cap layer and the hole-injection layer. It is also preferable to use a compound having a triarylamine skeleton for all of the cap layer, the hole-injection layer, and the hole-transport layer. The organic compounds described in Embodiment 1 can also be used.
The light-emitting device described in this embodiment can be formed over a variety of substrates. Note that the type of substrate is not limited to a certain type. Examples of the substrate include semiconductor substrates (e.g., a single crystal substrate and a silicon substrate), an SOI substrate, a glass substrate, a quartz substrate, a plastic substrate, a metal substrate, a stainless steel substrate, a substrate including stainless steel foil, a tungsten substrate, a substrate including tungsten foil, a flexible substrate, an attachment film, paper including a fibrous material, and a base material film including a fibrous material.
Examples of the glass substrate include barium borosilicate glass, aluminoborosilicate glass, and soda lime glass. Examples of the flexible substrate, the attachment film, and the base material film include plastics typified by polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyether sulfone (PES), a synthetic resin such as acrylic resin, polypropylene, polyester, polyvinyl fluoride, polyvinyl chloride, polyamide, polyimide, aramid, epoxy resin, an inorganic vapor deposition film, and paper.
For fabrication of the light-emitting device described in this embodiment, a vapor phase method such as an evaporation method or a liquid phase method such as a spin coating method and an ink-jet method can be used. When an evaporation method is used, a physical vapor deposition method (PVD method) such as a sputtering method, an ion plating method, an ion beam evaporation method, a molecular beam evaporation method, or a vacuum evaporation method, a chemical vapor deposition method (CVD method), or the like can be used. Specifically, layers having a variety of functions (the hole-injection layer 111, the hole-transport layer 112, the light-emitting layer 113, the electron-transport layer 114, and the electron-injection layer 115) included in the EL layer of the light-emitting device can be formed by an evaporation method (e.g., a vacuum evaporation method), a coating method (e.g., a dip coating method, a die coating method, a bar coating method, a spin coating method, or a spray coating method), a printing method (e.g., an ink-jet method, a screen printing (stencil) method, an offset printing (planography) method, a flexography (relief printing) method, a gravure printing method, or a micro-contact printing method), or the like.
In the case where a film formation method such as the coating method or the printing method is employed, a high molecular compound (e.g., an oligomer, a dendrimer, or a polymer), a middle molecular compound (a compound between a low molecular compound and a high molecular compound with a molecular weight of greater than or equal to 400 and less than or equal to 4000), an inorganic compound (e.g., a quantum dot material), or the like can be used. As the quantum dot material, a colloidal quantum dot material, an alloyed quantum dot material, a core-shell quantum dot material, a core quantum dot material, or the like can be used.
Materials that can be used for the layers (the hole-injection layer 111, the hole-transport layer 112, the light-emitting layer 113, the electron-transport layer 114, and the electron-injection layer 115) included in the EL layer 103 of the light-emitting device described in this embodiment are not limited to the materials described in this embodiment, and other materials can be used in combination as long as the functions of the layers are fulfilled.
Note that in this specification and the like, the term “layer” and the term “film” can be interchanged with each other as appropriate.
The compound of the present application can be used as a hole-transport material, a host material, an electron-transport material, a cap layer, or the like.
The structures described in this embodiment can be used in an appropriate combination with any of the structures described in the other embodiments.
This embodiment will describe a light-emitting and light-receiving apparatus 700 as a specific structure example of a light-emitting and light-receiving apparatus of one embodiment of the present invention, and an example of the manufacturing method thereof. The light-emitting and light-receiving apparatus 700 includes a light-emitting device and thus can be regarded as a light-emitting apparatus; includes a light-receiving device and thus can be regarded as a light-receiving apparatus; and can be used in a display portion in an electronic device and thus can be regarded as a display panel or a display apparatus.
The light-emitting and light-receiving apparatus 700 illustrated in
The light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R have the device structure described in Embodiment 2, and the light-receiving device 550PS has a device structure described later in Embodiment 8. Although this embodiment describes the case where the devices (a plurality of light-emitting devices and a light-receiving device) are formed separately, part of an EL layer of the light-emitting device (a hole-injection layer, a hole-transport layer, or an electron-transport layer) and part of an active layer of the light-receiving device (a first transport layer or a second transport layer) may be formed using the same material at the same time in the manufacturing process. The detailed description will be made in Embodiment 8.
Note that in this specification and the like, a structure where light-emitting layers in light-emitting devices of different colors (e.g., blue (B), green (G), and red (R)) and a light-receiving layer in a light-receiving device are separately formed or separately patterned may be referred to as an SBS (Side By Side) structure. Note that in the light-emitting and light-receiving apparatus 700 illustrated in
In
EL layer 103G, and the EL layer 103R each have a stacked-layer structure of layers having different functions including light-emitting layers (105B, 105G, and 105R). The light-receiving layer 103PS has a stacked-layer structure of layers having different functions including an active layer 105PS.
Note that the electron-transport layers (108B, 108G, and 108R) and the second transport layer 108PS may have a function of blocking holes moving from the anode side to the cathode side through the light-emitting layers (103B, 103G, and 103R) and the light-receiving layer 103PS of the light-receiving device. The electron-injection layer 109 may have a stacked-layer structure where some or all of layers are formed using different materials.
As illustrated in
PLD method, an ALD method, or the like and is formed preferably by an ALD method, which enables favorable coverage. Note that the insulating layer 107 continuously covers the side surfaces (or the end portions) of parts of the EL layers (103B, 103G, and 103R) and part of the light-receiving layer 103PS of adjacent devices. For example, in
In addition, the electron-injection layer 109 is formed over the electron-transport layers (108B, 108G, and 108R) that are parts of the EL layers (103B, 103G, and 103R), the second transport layer 108PS that is part of the light-receiving layer 103PS, and the insulating layer 107. Note that the electron-injection layer 109 may have a stacked-layer structure of two or more layers (for example, stacked layers having different electric resistances).
The electrode 552 is formed over the electron-injection layer 109. Note that the electrodes (551B, 551G, and 551R) and the electrode 552 have overlapping regions. The light-emitting layer 105B is provided between the electrode 551B and the electrode 552, the light-emitting layer 105G is provided between the electrode 551G and the electrode 552, the light-emitting layer 105R is provided between the electrode 551R and the electrode 552, and the light-receiving layer 103PS is provided between the electrode 551PS and the electrode 552.
The EL layers (103B, 103G, and 103R) illustrated in
The partition walls 528 are provided in regions surrounded by the electron-injection layer 109 and the insulating layer 107. As illustrated in
In each of the EL layers and the light-receiving layer, particularly the hole-injection layer, which is included in a hole-transport region between the anode and the light-emitting layer and a hole-transport region between the anode and the active layer, often has high conductivity; thus, the hole-injection layer formed as a layer shared by adjacent light-emitting devices might cause crosstalk. Thus, as described in this structure example, the partition walls 528 formed using an insulating material are provided between the EL layers and between the EL layer and the light-receiving layer, which can inhibit occurrence of crosstalk between adjacent devices.
In the manufacturing method described in this embodiment, side surfaces (or end portions) of the EL layer and the light-receiving layer are exposed in the patterning step. This may promote deterioration of the EL layer and the light-receiving layer by allowing entry of oxygen, water, or the like through the side surfaces (or the end portions) of the EL layer and the light-receiving layer. Thus, providing the partition wall 528 can inhibit the deterioration of the EL layer and the light-receiving layer in the manufacturing process.
Furthermore, a depressed portion formed between adjacent devices can be flattened by provision of the partition wall 528. When the depressed portion is flattened, disconnection of the electrode 552 formed over the EL layers and the light-receiving layer can be inhibited. As an insulating material used for forming the partition wall 528, an organic material such as an acrylic resin, a polyimide resin, an epoxy resin, an imide resin, a polyamide resin, a polyimide-amide resin, a silicone resin, a siloxane resin, a benzocyclobutene-based resin, a phenol resin, or precursors of these resins can be used, for example. An organic material such as polyvinyl alcohol (PVA), polyvinyl butyral, polyvinylpyrrolidone, polyethylene glycol, polyglycerin, pullulan, water-soluble cellulose, or an alcohol-soluble polyamide resin may be used. A photosensitive resin such as a photoresist can also be used. Note that as the photosensitive resin, a positive photosensitive material or a negative photosensitive material can be used.
With the use of the photosensitive resin, the partition wall 528 can be fabricated only by light exposure and development steps. The partition wall 528 may be formed using a negative photosensitive resin (e.g., a resist material). In the case where an insulating layer containing an organic material is used as the partition wall 528, a material absorbing visible light is suitably used. When a material absorbing visible light is used for the partition wall 528, light emitted from the EL layer can be absorbed by the partition wall 528, so that light that might leak to the adjacent EL layer or the adjacent light-receiving layer (stray light) can be inhibited. Thus, a display panel having high display quality can be provided.
The difference between the top-surface level of the partition wall 528 and the top-surface level of any of the EL layer 103B, the EL layer 103G, the EL layer 103R, and the light-receiving layer 103PS is preferably 0.5 times or less, further preferably 0.3 times or less the thickness of the partition wall 528, for example. The partition wall 528 may be provided such that the top-surface level of any of the EL layer 103B, the EL layer 103G, the EL layer 103R, and the light-receiving layer 103PS is higher than the top-surface level of the partition wall 528, for example. Alternatively, the partition wall 528 may be provided such that the top-surface level of the partition wall 528 is higher than the top-surface level of each of the EL layer 103B, the EL layer 103G, the EL layer 103R, and the light-receiving layer 103PS, for example.
When electrical continuity is established between the EL layer 103B, the EL layer 103G, the EL layer 103R, and the light-receiving layer 103PS in a light-emitting and light-receiving apparatus (display panel) with a high resolution exceeding 1000 ppi, a crosstalk phenomenon occurs, resulting in a narrower color gamut of the light-emitting and light-receiving apparatus. Providing the partition wall 528 in a high-resolution display panel with more than 1000 ppi, preferably more than 2000 ppi, or further preferably in an ultrahigh-resolution display panel with more than 5000 ppi allows the display panel to express vivid colors.
The EL layers (103B, 103G, and 103R) and the light-receiving layer 103PS are processed to be separated from each other by patterning using a photolithography method; hence, a high resolution light-emitting and light-receiving apparatus (display panel) can be manufactured. End portions (side surfaces) of the layers of the EL layer processed by patterning using a photolithography method have substantially the same surface (or are positioned on substantially the same plane). In addition, the side surfaces (end portions) of the layers of the light-receiving layer processed by patterning using a photolithography method have substantially the same surface (or are positioned on substantially the same plane). In this case, the width (SE) of a space 580 between the EL layers and between the EL layer and the light-receiving layer is preferably less than or equal to 5 μm, further preferably less than or equal to 1 μm. Note that the width of the space between the EL layer and the light-receiving layer is preferably greater than the width of the space between the EL layers.
In the EL layer, particularly the hole-injection layer, which is included in the hole-transport region between the anode and the light-emitting layer, often has high conductivity; thus, the hole-injection layer formed as a layer shared by adjacent light-emitting devices might cause crosstalk. Therefore, processing the EL layers to be separated by patterning using a photolithography method as shown in this structure example can inhibit occurrence of crosstalk between adjacent light-emitting devices.
The electrode 551B, the electrode 551G, the electrode 551R, and the electrode 551PS are formed as illustrated in
The conductive film can be formed by a sputtering method, a chemical vapor deposition (CVD) method, a molecular beam epitaxy (MBE) method, a vacuum evaporation method, a pulsed laser deposition (PLD) method, an atomic layer deposition (ALD) method, or the like. Examples of the CVD method include a plasma-enhanced chemical vapor deposition (PECVD) method and a thermal CVD method. As an example of the thermal CVD method, a metal organic chemical vapor deposition (MOCVD: Metal Organic CVD) method can be given.
The conductive film may be processed by a nanoimprinting method, a sandblasting method, a lift-off method, or the like as well as a photolithography method described above. Alternatively, island-shaped thin films may be directly formed by a film formation method using a shielding mask such as a metal mask.
There are the following two typical examples of a photolithography method. In one of the methods, a resist mask is formed over a thin film that is to be processed, the thin film is processed by etching or the like, and then the resist mask is removed. In the other method, a photosensitive thin film is formed and then processed into a desired shape by light exposure and development. The former method involves heat treatment steps such as heating after resist application (PAB: Pre Applied Bake) and heating after light exposure (PEB: Post Exposure Bake). In one embodiment of the present invention, a lithography method is used not only for processing of a conductive film but also for processing of a thin film used for formation of an EL layer (a film made of an organic compound or a film partly including an organic compound).
As the light used for light exposure in the photolithography method, for example, an i-line (with a wavelength of 365 nm), a g-line (with a wavelength of 436 nm), an h-line (with a wavelength of 405 nm), or combined light of any of them can be used. Alternatively, ultraviolet rays, KrF laser light, ArF laser light, or the like can be used. In addition, light exposure may be performed by liquid immersion exposure technique. As the light for light exposure, extreme ultraviolet (EUV) light or X-rays may also be used. Furthermore, instead of the light used for the light exposure, an electron beam can also be used. It is preferable to use extreme ultraviolet light, X-rays, or an electron beam because they can perform extremely fine processing. Note that a photomask is not needed when light exposure is performed by scanning with a beam such as an electron beam.
For etching of a thin film using a resist mask, a dry etching method, a wet etching method, a sandblast method, or the like can be used.
Subsequently, as illustrated in
For the sacrificial layer 110B, it is preferable to use a film highly resistant to etching treatment performed on the hole-injection/transport layer 104B, the light-emitting layer 105B, and the electron-transport layer 108B, i.e., a film having high etching selectivity. The sacrificial layer 110B preferably has a stacked-layer structure of a first sacrificial layer and a second sacrificial layer which have different etching selectivities. Moreover, for the sacrificial layer 110B, it is possible to use a film that can be removed by a wet etching method less likely to cause damage to the EL layer 103B. In wet etching, oxalic acid or the like can be used as an etching material.
The sacrificial layer 110B can be formed using an inorganic film such as a metal film, an alloy film, a metal oxide film, a semiconductor film, or an inorganic insulating film, for example. The sacrificial layer 110B can be formed by any of a variety of film formation methods such as a sputtering method, an evaporation method, a CVD method, and an ALD method.
For the sacrificial layer 110B, a metal material such as gold, silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper, palladium, titanium, aluminum, yttrium, zirconium, or tantalum or an alloy material containing the metal material can be used. It is particularly preferable to use a low-melting-point material such as aluminum or silver.
The sacrificial layer 110B can be formed using a metal oxide such as indium gallium zinc oxide (In—Ga—Zn oxide, also referred to as IGZO). It is also possible to use indium oxide, indium zinc oxide (In—Zn oxide), indium tin oxide (In—Sn oxide), indium titanium oxide (In—Ti oxide), indium tin zinc oxide (In—Sn—Zn oxide), indium titanium zinc oxide (In—Ti—Zn oxide), indium gallium tin zinc oxide (In—Ga—Sn—Zn oxide), or the like. Alternatively, indium tin oxide containing silicon or the like can also be used.
Note that an element M (M is one or more kinds selected from aluminum, silicon, boron, yttrium, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium) can be employed instead of gallium. In particular, M is preferably one or more kinds selected from gallium, aluminum, and yttrium.
For the sacrificial layer 110B, an inorganic insulating material such as aluminum oxide, hafnium oxide, or silicon oxide can be used.
The sacrificial layer 110B is preferably formed using a material that can be dissolved in a solvent chemically stable with respect to the electron-transport layer 108B, which is the uppermost layer. In particular, a material that will be dissolved in water or alcohol can be suitably used for the sacrificial layer 110B. In formation of the sacrificial layer 110B, it is preferable that application of such a material dissolved in a solvent such as water or alcohol be performed by a wet film formation method and followed by heat treatment for evaporating the solvent. At this time, the heat treatment is preferably performed in a reduced-pressure atmosphere, in which case the solvent can be removed at a low temperature in a short time and thermal damage to the hole-injection/transport layer 104B, the light-emitting layer 105B, and the electron-transport layer 108B can be reduced accordingly.
In the case where the sacrificial layer 110B having a stacked-layer structure is formed, the stacked-layer structure can include the first sacrificial layer formed using any of the above-described materials and the second sacrificial layer formed thereover.
The second sacrificial layer in that case is a film used as a hard mask for etching of the first sacrificial layer. In processing the second sacrificial layer, the first sacrificial layer is exposed. Thus, a combination of films having high etching selectivity therebetween is selected for the first sacrificial layer and the second sacrificial layer. Thus, a film that can be used for the second sacrificial layer can be selected in accordance with the etching conditions of the first sacrificial layer and the etching conditions of the second sacrificial layer.
For example, in the case where dry etching using a gas containing fluorine (also referred to as a fluorine-based gas) is performed for the etching of the second sacrificial layer, silicon, silicon nitride, silicon oxide, tungsten, titanium, molybdenum, tantalum, tantalum nitride, an alloy containing molybdenum and niobium, an alloy containing molybdenum and tungsten, or the like can be used for the second sacrificial layer. Here, a metal oxide film of IGZO, ITO, or the like is given as an example of a film having high etching selectivity (that is, enabling low etching rate) in dry etching using the fluorine-based gas, and such a film can be used as the first sacrificial layer.
Note that the material for the second sacrificial layer is not limited to the above and can be selected from a variety of materials in accordance with the etching conditions of the first sacrificial layer and the etching conditions of the second sacrificial layer. For example, any of the films that can be used for the first sacrificial layer can be selected.
As the second sacrificial layer, a nitride film can be used, for example. Specifically, it is possible to use a nitride such as silicon nitride, aluminum nitride, hafnium nitride, titanium nitride, tantalum nitride, tungsten nitride, gallium nitride, or germanium nitride.
Alternatively, an oxide film can be used as the second sacrificial layer. Typically, a film of an oxide or an oxynitride such as silicon oxide, silicon oxynitride, aluminum oxide, aluminum oxynitride, hafnium oxide, or hafnium oxynitride can be used.
Next, as illustrated in
Next, part of the sacrificial layer 110B which is not covered with the resist mask REG is removed by etching using the obtained resist mask REG, the resist mask REG is removed, and then parts of the hole-injection/transport layer 104B, the light-emitting layer 105B, and the electron-transport layer 108B which are not covered with the sacrificial layer 110B are removed by etching, so that the hole-injection/transport layer 104B, the light-emitting layer 105B, and the electron-transport layer 108B are processed to have side surfaces (or have their side surfaces exposed) over the electrode 551B or have belt-like shapes extending in the direction intersecting the sheet. Note that dry etching is preferably employed for the etching. In the case where the sacrificial layer 110B has the aforementioned stacked-layer structure of the first sacrificial layer and the second sacrificial layer, the hole-injection/transport layer 104B, the light-emitting layer 105B, and the electron-transport layer 108B may be processed into desired shapes in the following manner: part of the second sacrificial layer is etched using the resist mask REG, the resist mask REG is then removed, and part of the first sacrificial layer is etched using the second sacrificial layer as a mask. The shape in
Subsequently, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
For formation of the insulating layer 107, an ALD method can be used, for example. In this case, as illustrated in
Then, as illustrated in
Next, as illustrated in
Through the above steps, the EL layer 103B, the EL layer 103G, the EL layer 103R, and the light-receiving layer 103PS in the light-emitting device 550B, the light-emitting device 550G, the light-emitting device 550R, and the light-receiving layer 550PS can be processed to be separated from each other.
The EL layers (103B, 103G, and 103R) and the light-receiving layer 103PS are processed to be separated by patterning using a photolithography method; hence, a light-emitting and light-receiving apparatus (display panel) with a high resolution can be manufactured. End portions (side surfaces) of the layers of the EL layer processed by patterning using a photolithography method have substantially the same surface (or are positioned on substantially the same plane). In addition, the side surfaces (end portions) of the layers of the light-receiving layer processed by patterning using a photolithography method have substantially the same surface (or are positioned on substantially the same plane).
The hole-injection/transport layers (104B, 104G, and 104R) of the EL layers and the first transport layer 104PS of the light-receiving layer often have high conductivity, and thus might cause crosstalk when formed as layers shared by adjacent devices. Therefore, processing the layers to be separated from each other by patterning using a photolithography method as described in this structure example can inhibit occurrence of crosstalk between adjacent devices.
In this structure example, the hole-injection/transport layers (104B, 104G, and 104R), the light-emitting layers (105B, 105G, and 105R), and the electron-transport layers (108B, 108G, and 108R) of the EL layers (103B, 103G, and 103R) included in the light-emitting devices and the first transport layer 104PS, the active layer 105PS, and the second transport layer 108PS of the light-receiving layer 103PS included in the light-receiving device are processed to be separated by patterning using a photolithography method; thus, the end portions (side surfaces) of the processed layers of the EL layer have substantially the same surface (or are positioned on substantially the same plane). In addition, the side surfaces (end portions) of the layers of the light-receiving layer processed by patterning using a photolithography method have substantially the same surface (or are positioned on substantially the same plane).
In addition, the hole-injection/transport layers (104B, 104G, and 104R), the light-emitting layers (105B, 105G, and 105R), and the electron-transport layers (108B, 108G, and 108R) of the EL layers (103B, 103G, and 103R) included in the light-emitting devices and the first transport layer 104PS, the active layer 105PS, and the second transport layer 108PS of the light-receiving layer 103PS included in the light-receiving device are processed to be separated by patterning using a photolithography method. Thus, the space 580 is provided between the processed end portions (side surfaces) of adjacent light-emitting devices. In
In this specification and the like, a device manufactured using a metal mask or an FMM (a fine metal mask, a high-resolution metal mask) is sometimes referred to as a device having an MM (metal mask) structure. In this specification and the like, a device manufactured without using a metal mask or an FMM is sometimes referred to as a device having an MML (metal maskless) structure. A light-emitting apparatus having an MML structure is formed without using a metal mask and thus has higher flexibility in designing the pixel arrangement, the pixel shape, and the like than a light-emitting apparatus having an FMM structure or an MM structure.
Note that an island-shaped EL layer of a light-emitting and light-receiving apparatus having an MML structure is formed not by patterning using a metal mask but by processing after formation of an EL layer. Accordingly, a light-emitting and light-receiving apparatus with a higher resolution or a higher aperture ratio than a conventional one can be achieved. Moreover, EL layers can be formed separately for the respective colors, enabling the light-emitting and light-receiving apparatus to perform extremely clear display with high contrast and high display quality. Moreover, providing the sacrificial layer over the EL layer can reduce damage to the EL layer in the manufacturing process, resulting in an increase in the reliability of the light-emitting device.
The compound including an azine skeleton of one embodiment of the present invention (also referred to as the compound of the present application), which is described in Embodiment 1 or the like, has a feature of high heat resistance or the like; thus, the use of the compound for an electron-transport/injection layer, an electron-transport layer, a light-emitting layer, a hole-transport layer, a hole-injection layer, an intermediate layer, or a cap layer can enhance the effect of reducing damage during the fabrication process of the MML structure. In particular, the use of the compound of the present application for a layer in an upper position, such as a cap layer, an electron-injection layer, or an electron-transport layer, can reduce damage to layers in a lower position. For example, in the case where the compound of the present application is used for the electron-transport layer, a material with a higher Tg than the host material in the light-emitting layer is preferably used as the compound. Similarly, in the case where the compound of the present application is used for the electron-transport layer, a material with a higher Tg than the hole-transport layer material is preferably used as the compound. As the compound including an azine skeleton, any of the compounds represented by General Formulae (G1) to (G4) described in Embodiment 1 is preferably used; however, the present invention is not limited thereto.
In the case where the compound of the present application is used for a common layer such as the electron-injection layer 109, the electron-injection layer 109 and the partition wall 528 are preferably placed to overlap with each other. The compound of the present application has a high Tg and thus can reduce damage to the partition wall 528. The transport layer (the electron-transport layer 108B, the electron-transport layer 108G, the electron-transport layer 108R, or the second transport layer 108PS) may be formed over the partition wall 528. In that case, it is preferable to use the compound of the present application for the transport layer and place the transport layer and the partition wall to overlap with each other. It is also effective to place a layer including the compound of the present application to overlap with the partition wall between the light-receiving device 550PS and the light-emitting device. Note that the electron-transport layer 108B, the electron-transport layer 108G, the electron-transport layer 108R, and the second transport layer 108PS may be provided not as separate layers but as a continuous layer.
It is effective to employ the compound of the present application with high resistance (heat resistance, stability, or the like) for a bendable device (also referred to as flexible device) that uses a flexible substrate as a substrate. For example, it is effective to provide a layer including the compound of the present application to overlap with a bent portion on which load is likely to be applied. The compound of the present application may be placed to overlap with a space between the partition wall 528 and the bent portion. In a device including a plurality of bent portions or in a wind-up device, many bent portions are included; thus, a cap layer and a layer including the compound of the present application are preferably provided to overlap with each other in each of the bent portions. It is also preferable to place the cap layer, the layer including the compound of the present invention, and the partition wall to overlap with each other in each of the bent portions.
In
In the light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R, the widths of the EL layers (103B, 103G, and 103R) may be smaller than the widths of the electrodes (551B, 551G, and 551R). In the light-receiving device 550PS, the width of the light-receiving layer 103PS may be smaller than the width of the electrode 551PS.
In the light-emitting device 550B, the light-emitting device 550G, and the light-emitting device 550R, the widths of the EL layers (103B, 103G, and 103R) may be larger than the widths of the electrodes (551B, 551G, and 551R). In the light-receiving device 550PS, the width of the light-receiving layer 103PS may be larger than the width of the electrode 551PS.
The structures described in this embodiment can be used in an appropriate combination with any of the structures described in the other embodiments.
In this embodiment, an apparatus 720 will be described with reference to
Furthermore, the light-emitting apparatus, the display panel, the display apparatus, and the light-emitting and light-receiving apparatus of this embodiment can each have a high definition or a large size. Accordingly, the light-emitting apparatus, the display panel, the display apparatus, and the light-emitting and light-receiving apparatus can be used for display portions of electronic appliances such as a digital camera, a digital video camera, a digital photo frame, a mobile phone, a portable game console, a smartphone, a wristwatch terminal, a tablet terminal, a portable information terminal, and an audio reproducing device, in addition to display portions of electronic appliances with a relatively large screen, such as a television device, a desktop or notebook personal computer, a monitor of a computer or the like, digital signage, and a large game machine such as a pachinko machine.
In
Furthermore, as illustrated in the example of
The wiring 706 has a function of supplying signals and power to the display region 701 and the circuit 704. The signals and power are input to the wiring 706 from the outside through an FPC (Flexible Printed Circuit) 713 or to the wiring 706 from the IC 712. Note that the apparatus 720 is not necessarily provided with the IC. The IC may be mounted on the FPC by a COF method or the like.
The apparatus 720 includes not only a subpixel including a light-emitting device, but also a subpixel including a light-receiving device.
Furthermore, as illustrated in
Note that the arrangement of subpixels is not limited to the structures illustrated in
Examples of a top surface shape of the subpixel include polygons such as a triangle, a tetragon (including a rectangle and a square), and a pentagon; polygons with rounded corners; an ellipse; and a circle. Here, the top surface shape of the subpixel corresponds to a top surface shape of a light-emitting region of the light-emitting device.
In the case where a pixel includes a light-receiving device in addition to a light-emitting device, the pixel has a light-receiving function; thus, a touch or an approach of an object can be detected while an image is being displayed. For example, all the subpixels included in the light-emitting apparatus can display an image; alternatively, some of the subpixels can emit light as a light source, and the rest of the subpixels can display an image.
Note that the light-receiving area of the subpixel 702PS(i, j) is preferably smaller than the light-emitting areas of the other subpixels. A smaller light-receiving area leads to a narrower image-capturing range, inhibits a blur in a capturing result, and improves the definition. Thus, by using the subpixel 702PS(i, j), high-resolution or high-definition image capturing is possible. For example, image capturing for personal authentication with the use of a fingerprint, a palm print, the iris, the shape of a blood vessel (including the shape of a vein and the shape of an artery), a face, or the like is possible by using the subpixel 702PS(i, j).
Moreover, the subpixel 702PS(i, j) can be used in a touch sensor (also referred to as a direct touch sensor), a near touch sensor (also referred to as a hover sensor, a hover touch sensor, a contactless sensor, or a touchless sensor), or the like. For example, the subpixel 702PS(i, j) preferably detects infrared light. Thus, a touch can be detected even in a dark place.
Here, the touch sensor or the near touch sensor can detect the approach or contact of an object (e.g., a finger, a hand, or a pen). The touch sensor can detect the object when the light-emitting and light-receiving apparatus and the object come in direct contact with each other. Furthermore, the near touch sensor can detect the object even when the object is not in contact with the light-emitting and light-receiving apparatus. For example, the display apparatus is preferably capable of detecting an object positioned in the range of 0.1 mm to 300 mm inclusive, further preferably 3 mm to 50 mm inclusive from the light-emitting and light-receiving apparatus. This structure enables the light-emitting and light-receiving apparatus to be operated without direct contact of an object, that is, enables the light-emitting and light-receiving apparatus to be operated in a contactless (touchless) manner. With the above-described structure, the light-emitting and light-receiving apparatus can be operated with a reduced risk of making the light-emitting and light-receiving apparatus dirty or damaging the light-emitting and light-receiving apparatus or without the object directly touching a dirt (e.g., dust, bacteria, or a virus) attached to the light-emitting and light-receiving apparatus.
For high-resolution image capturing, the subpixels 702PS(i, j) are preferably provided in all pixels included in the light-emitting and light-receiving apparatus. Meanwhile, in the case where the subpixel 702PS(i, j) is used in a touch sensor, a near touch sensor, or the like, high accuracy is not required as compared to the case of capturing an image of a fingerprint or the like; accordingly, the subpixel 702PS(i, j) may be provided in some pixels in the light-emitting and light-receiving apparatus. When the number of the subpixels 702PS(i, j) included in the light-emitting and light-receiving apparatus is smaller than the number of the subpixels 702R(i, j) or the like, higher detection speed can be achieved.
Next, an example of a pixel circuit of a subpixel including the light-emitting device is described with reference to
In the transistor M15 illustrated in
A constant potential is supplied to the wiring V4 and the wiring V5. In the light-emitting device 550, the anode side can have a high potential and the cathode side can have a lower potential than the anode side. The transistor M15 is controlled by a signal supplied to the wiring VG and functions as a selection transistor for controlling a selection state of the pixel circuit 530. The transistor M16 functions as a driving transistor that controls a current flowing through the light-emitting device 550 in accordance with a potential supplied to the gate of the transistor M16. When the transistor M15 is in a conduction state, a potential supplied to the wiring VS is supplied to the gate of the transistor M16, and the emission luminance of the light-emitting device 550 can be controlled in accordance with the potential. The transistor M17 is controlled by a signal supplied to the wiring MS and has a function of outputting a potential between the transistor M16 and the light-emitting device 550 to the outside through the wiring OUT2.
Here, transistors in which a metal oxide (an oxide semiconductor) is used in a semiconductor layer where a channel is formed are preferably used as the transistor M15, the transistor M16, and the transistor M17 included in the pixel circuit 530 illustrated in
A transistor using a metal oxide having a wider band gap and a lower carrier density than silicon achieves an extremely low off-state current. Therefore, owing to the low off-state current, charge accumulated in a capacitor that is connected in series to the transistor can be retained for a long time. Accordingly, it is particularly preferable to use transistors containing an oxide semiconductor as the transistor M11, the transistor M12, and the transistor M15 each of which is connected in series to a capacitor C2 or the capacitor C3. When transistors using an oxide semiconductor are used as the other transistors, the manufacturing cost can be reduced.
Alternatively, transistors using silicon for a semiconductor where a channel is formed can be used as the transistor M11 to the transistor M17. It is particularly preferable to use silicon with high crystallinity, such as single crystal silicon or polycrystalline silicon, because high field-effect mobility can be achieved and higher-speed operation can be performed.
Alternatively, a transistor using an oxide semiconductor may be used as one or more of the transistor M11 to the transistor M17, and transistors using silicon may be used as the other transistors.
Next, an example of a pixel circuit of a subpixel including a light-receiving device is described with reference to
In the light-receiving device (PD) 560 illustrated in
A constant potential is supplied to each of the wiring V1, the wiring V2, and the wiring V3. When the light-receiving device (PD) 560 is driven with a reverse bias, the wiring V2 is supplied with a potential higher than the potential of the wiring V1. The transistor M12 is controlled by a signal supplied to the wiring RES and has a function of resetting the potential of a node connected to the gate of the transistor M13 to a potential supplied to the wiring V2. The transistor M11 is controlled by a signal supplied to the wiring TX and has a function of controlling the timing at which the potential of the node changes, in accordance with a current flowing through the light-receiving device (PD) 560. The transistor M13 functions as an amplifier transistor for performing output corresponding to the potential of the node. The transistor M14 is controlled by a signal supplied to the wiring SE1 and functions as a selection transistor for making an external circuit connected to the wiring OUT1 read the output corresponding to the potential of the node. Although n-channel transistors are shown as the transistors in
The transistors included in the pixel circuit 530 and the transistors included in the pixel circuit 531 are preferably formed to be arranged over the same substrate. It is particularly preferable that the transistors included in the pixel circuit 530 and the transistors included in the pixel circuit 531 be periodically arranged in one region.
One or more layers including the transistor and/or the capacitor are preferably provided to overlap with the light-receiving device (PD) 560 or the light-emitting device (EL) 550. Thus, the effective area occupied by each pixel circuit can be reduced, and a high-resolution light-receiving portion or display portion can be achieved.
The transistor illustrated in
The semiconductor film 508 includes a region 508A electrically connected to the conductive film 512A and a region 508B electrically connected to the conductive film 512B. The semiconductor film 508 includes a region 508C between the region 508A and the region 508B.
The conductive film 504 includes a region overlapping with the region 508C and has a function of a gate electrode.
The insulating film 506 includes a region interposed between the semiconductor film 508 and the conductive film 504. The insulating film 506 has a function of a first gate insulating film.
The conductive film 512A has one of a function of a source electrode and a function of a drain electrode, and the conductive film 512B has the other of the function of the source electrode and the function of the drain electrode.
A conductive film 524 can be used in the transistor. The conductive film 524 includes a region where the semiconductor film 508 is interposed between the conductive film 504 and the conductive film 524. The conductive film 524 has a function of a second gate electrode. An insulating film 501D is interposed between the semiconductor film 508 and the conductive film 524 and has a function of a second gate insulating film.
The insulating film 516 functions as, for example, a protective film covering the semiconductor film 508. Specifically, a film including a silicon oxide film, a silicon oxynitride film, a silicon nitride oxide film, a silicon nitride film, an aluminum oxide film, a hafnium oxide film, an yttrium oxide film, a zirconium oxide film, a gallium oxide film, a tantalum oxide film, a magnesium oxide film, a lanthanum oxide film, a cerium oxide film, or a neodymium oxide film can be used as the insulating film 516, for example.
For example, a material having a function of inhibiting diffusion of oxygen, hydrogen, water, an alkali metal, an alkaline earth metal, and the like is preferably used for the insulating film 518. Specifically, the insulating film 518 can be formed using silicon nitride, silicon oxynitride, aluminum nitride, or aluminum oxynitride, for example. In each of silicon oxynitride and aluminum oxynitride, the number of nitrogen atoms contained is preferably larger than the number of oxygen atoms contained.
Note that in a step of forming the semiconductor film used in the transistor of the pixel circuit, the semiconductor film used in the transistor of the driver circuit can be formed. A semiconductor film with the same composition as the semiconductor film used in the transistor of the pixel circuit can be used in the driver circuit, for example.
The semiconductor film 508 preferably contains indium, M (M is one or more kinds selected from gallium, aluminum, silicon, boron, yttrium, tin, copper, vanadium, beryllium, titanium, iron, nickel, germanium, zirconium, molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and magnesium), and zinc, for example. Specifically, M is preferably one or more kinds selected from aluminum, gallium, yttrium, and tin.
It is particularly preferable that an oxide containing indium (In), gallium (Ga), and zinc (Zn) (also referred to as IGZO) be used for the semiconductor film 508. Alternatively, it is preferable to use an oxide containing indium, tin, and zinc. Further alternatively, it is preferable to use an oxide containing indium, gallium, tin, and zinc. Alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), and zinc (Zn) (also referred to as IAZO). Further alternatively, it is preferable to use an oxide containing indium (In), aluminum (Al), gallium (Ga), and zinc (Zn) (also referred to as IAGZO).
In the case where the semiconductor film is an In-M-Zn oxide, the atomic proportion of In is preferably greater than or equal to the atomic proportion of M in the In-M-Zn oxide.
Examples of the atomic ratio of the metal elements in such an In-M-Zn oxide include In:M:Zn=1:1:1 or a composition in the neighborhood thereof, In:M:Zn=1:1:1.2 or a composition in the neighborhood thereof, In:M:Zn=1:3:2 or a composition in the neighborhood thereof, In:M:Zn=1:3:4 or a composition in the neighborhood thereof, In:M:Zn=2:1:3 or a composition in the neighborhood thereof, In:M:Zn=3:1:2 or a composition in the neighborhood thereof, In:M:Zn=4:2:3 or a composition in the neighborhood thereof, In:M:Zn=4:2:4.1 or a composition in the neighborhood thereof, In:M:Zn=5:1:3 or a composition in the neighborhood thereof, In:M:Zn=5:1:6 or a composition in the neighborhood thereof, In:M:Zn=5:1:7 or a composition in the neighborhood thereof, In:M:Zn=5:1:8 or a composition in the neighborhood thereof, In:M:Zn=6:1:6 or a composition in the neighborhood thereof, and In:M:Zn=5:2:5 or a composition in the neighborhood thereof. Note that a composition in the neighborhood includes the range of +30% of an intended atomic ratio.
For example, when the atomic ratio is described as In:Ga:Zn=4:2:3 or a composition in the neighborhood thereof, the case is included where the atomic ratio of Ga is greater than or equal to 1 and less than or equal to 3 and the atomic ratio of Zn is greater than or equal to 2 and less than or equal to 4 with the atomic ratio of In being 4. When the atomic ratio is described as In:Ga:Zn=5:1:6 or a composition in the neighborhood thereof, the case is included where the atomic ratio of Ga is greater than 0.1 and less than or equal to 2 and the atomic ratio of Zn is greater than or equal to 5 and less than or equal to 7 with the atomic ratio of In being 5. When the atomic ratio is described as In:Ga:Zn=1:1:1 or a composition in the neighborhood thereof, the case is included where the atomic ratio of Ga is greater than 0.1 and less than or equal to 2 and the atomic ratio of Zn is greater than 0.1 and less than or equal to 2 with the atomic ratio of In being 1.
There is no particular limitation on the crystallinity of a semiconductor material used for the transistors, and any of an amorphous semiconductor and a semiconductor having crystallinity (a microcrystalline semiconductor, a polycrystalline semiconductor, a single crystal semiconductor, or a semiconductor partly including crystal regions) may be used. A semiconductor having crystallinity is preferably used, in which case degradation of the transistor characteristics can be inhibited.
The semiconductor layer of the transistor preferably includes a metal oxide (also referred to as an oxide semiconductor). As the oxide semiconductor having crystallinity, a CAAC (c-axis aligned crystalline)-OS, an nc (nanocrystalline)-OS, and the like are given.
Alternatively, a transistor using silicon in a channel formation region (a Si transistor) may be used. Examples of silicon include single crystal silicon (single crystal Si), polycrystalline silicon, and amorphous silicon. In particular, a transistor containing low-temperature polysilicon (LTPS) in its semiconductor layer (hereinafter also referred to as an LTPS transistor) can be used. The LTPS transistor has high field-effect mobility and favorable frequency characteristics.
With the use of a Si transistor such as an LTPS transistor, a circuit required to be driven at a high frequency (e.g., a source driver circuit) can be formed on the same substrate as the display portion. This allows simplification of an external circuit mounted on the light-emitting apparatus and a reduction in component cost and mounting cost.
An OS transistor has much higher field-effect mobility than a transistor using amorphous silicon. In addition, an OS transistor has an extremely low leakage current between a source and a drain in an off state (hereinafter also referred to as off-state current), and charge accumulated in a capacitor that is connected in series to the transistor can be retained for a long period. Furthermore, the power consumption of the light-emitting apparatus can be reduced with the OS transistor.
The off-state current value per micrometer of channel width of the OS transistor at room temperature can be lower than or equal to 1 aA (1×10−18 A), lower than or equal to 1 zA (1×10−21 A), or lower than or equal to 1 yA (1×10−24 A). Note that the off-state current value per micrometer of channel width of a Si transistor at room temperature is higher than or equal to 1 fA (1×10−15 A) and lower than or equal to 1 pA (1×10−12 A). In other words, the off-state current of an OS transistor is lower than that of a Si transistor by approximately ten orders of magnitude.
To increase the emission luminance of the light-emitting device included in a pixel circuit, it is necessary to increase the amount of current flowing through the light-emitting device. For that purpose, the source-drain voltage of the driving transistor included in the pixel circuit needs to be increased. Since an OS transistor has a higher withstand voltage between the source and the drain than a Si transistor, a high voltage can be applied between the source and the drain of the OS transistor. Thus, with use of an OS transistor as a driving transistor included in the pixel circuit, the amount of current flowing through the light-emitting device can be increased, resulting in an increase in emission luminance of the light-emitting device.
When a transistor operates in a saturation region, a change in source-drain current relative to a change in gate-source voltage can be smaller in an OS transistor than in a Si transistor. Accordingly, when an OS transistor is used as the driving transistor included in the pixel circuit, current flowing between the source and the drain can be set minutely by a change in gate-source voltage; hence, the amount of current flowing through the light-emitting device can be controlled. Accordingly, the number of gray levels in the pixel circuit can be increased.
Regarding saturation characteristics of current flowing when a transistor operates in a saturation region, even in the case where the source-drain voltage of an OS transistor increases gradually, more stable current (saturation current) can be made flow through an OS transistor than through a Si transistor. Thus, with use of an OS transistor as a driving transistor, current can be made flow stably through the light-emitting device, for example, even when a variation in current-voltage characteristics of the light-emitting device occurs. In other words, when the OS transistor operates in the saturation region, the source-drain current hardly changes with an increase in the source-drain voltage; hence, the emission luminance of the light-emitting device can be stable.
As described above, with use of an OS transistor as the driving transistor included in the pixel circuit, it is possible to achieve “inhibition of black floating”, “increase in emission luminance”, “increase in the number of gray levels”, “inhibition of variation in light-emitting devices”, and the like.
The semiconductor film used in the transistor of the driver circuit can be formed in the same step as the semiconductor film used in the transistor of the pixel circuit. The driver circuit can be formed over a substrate where the pixel circuit is formed. The number of components of an electronic appliance can be reduced.
Silicon may be used for the semiconductor film 508. Examples of silicon include single crystal silicon, polycrystalline silicon, and amorphous silicon. In particular, a transistor containing low-temperature polysilicon (LTPS) in its semiconductor layer (hereinafter also referred to as an LTPS transistor) is preferably used. The LTPS transistor has high field-effect mobility and favorable frequency characteristics.
With the use of a transistor containing silicon, such as an LTPS transistor, a circuit required to be driven at a high frequency (e.g., a source driver circuit) can be formed on the same substrate as the display portion. This allows simplification of an external circuit mounted on the light-emitting apparatus and a reduction in component cost and mounting cost.
It is preferable to use a transistor containing a metal oxide (hereinafter also referred to as an oxide semiconductor) in its semiconductor where a channel is formed (hereinafter also referred to as an OS transistor) as at least one of the transistors included in the pixel circuit. An OS transistor has much higher field-effect mobility than a transistor using amorphous silicon. In addition, an OS transistor has an extremely low leakage current between a source and a drain in an off state (hereinafter also referred to as off-state current), and charge accumulated in a capacitor that is connected in series to the transistor can be retained for a long period. Furthermore, the power consumption of the light-emitting apparatus can be reduced with the OS transistor.
When LTPS transistors are used as some of the transistors included in the pixel circuit and OS transistors are used as the rest, the light-emitting apparatus can have low power consumption and high driving capability. As a favorable example, it is preferable that an OS transistor be used as a transistor functioning as a switch for controlling electrical continuity between wirings and an LTPS transistor be used as a transistor for controlling current. Note that a structure where an LTPS transistor and an OS transistor are combined is referred to as LTPO in some cases. LTPO enables the display panel to have low power consumption and high driving capability.
For example, one transistor provided in the pixel circuit functions as a transistor for controlling current flowing through the light-emitting device and can also be referred to as a driving transistor. One of a source and a drain of the driving transistor is electrically connected to the pixel electrode of the light-emitting device. An LTPS transistor is preferably used as the driving transistor. Thus, current flowing through the light-emitting device in the pixel circuit can be increased.
In contrast, another transistor provided in the pixel circuit functions as a switch for controlling selection and non-selection of a pixel and can also be referred to as a selection transistor. A gate of the selection transistor is electrically connected to a gate line, and one of a source and a drain thereof is electrically connected to a source line (signal line). An OS transistor is preferably used as the selection transistor. Accordingly, the gray level of the pixel can be maintained even with an extremely low frame frequency (e.g., 1 fps or less); thus, power consumption can be reduced by stopping the driver in displaying a still image.
In the case of using an oxide semiconductor in a semiconductor film, the apparatus 720 includes a light-emitting device using an oxide semiconductor in its semiconductor film and having an MML (metal maskless) structure. With this structure, the leakage current that might flow through the transistor and the leakage current that might flow between adjacent light-emitting devices (also referred to as lateral leakage current, side leakage current, or the like) can be extremely low. With the structure, a viewer can notice any one or more of the image crispness, the image sharpness, a high chroma, and a high contrast ratio in an image displayed on the display apparatus. When the leakage current that might flow through the transistor and the lateral leakage current that might flow between light-emitting devices are extremely low, display with little leakage of light at the time of black display (what is called black floating) (such display is also referred to as deep black display) can be achieved.
In particular, in the case where a light-emitting device having an MML structure employs the above-described SBS structure, a layer provided between light-emitting devices (for example, also referred to as an organic layer or a common layer which is shared by the light-emitting devices) is divided; accordingly, display with no or extremely small lateral leakage can be achieved.
The structure of transistors used in a display panel may be selected as appropriate depending on the screen size of the display panel. For example, single crystal Si transistors can be used in the display panel with a screen diagonal greater than or equal to 0.1 inches and less than or equal to 3 inches. In addition, LTPS transistors can be used in the display panel with a screen diagonal greater than or equal to 0.1 inches and less than or equal to 30 inches, preferably greater than or equal to 1 inch and less than or equal to 30 inches. In addition, an LTPO structure (where an LTPS transistor and an OS transistor are used in combination) can be used in the display panel with a screen diagonal greater than or equal to 0.1 inches and less than or equal to 50 inches, preferably greater than or equal to 1 inch and less than or equal to 50 inches. In addition, OS transistors can be used in the display panel with a screen diagonal greater than or equal to 0.1 inches and less than or equal to 200 inches, preferably greater than or equal to 50 inches and less than or equal to 100 inches.
Note that with use of single crystal Si transistors, an increase in screen size is extremely difficult because of the size of a single crystal Si substrate. Furthermore, since a laser crystallization apparatus is used in the manufacturing process, LTPS transistors are unlikely to respond to an increase in screen size (typically to a screen diagonal greater than 30 inches). By contrast, since the manufacturing process does not necessarily require a laser crystallization apparatus or the like or can be performed at a relatively low process temperature (typically, lower than or equal to 450° C.), OS transistors can be used for a display panel with a relatively large area (typically, a screen diagonal greater than or equal to 50 inches and less than or equal to 100 inches). In addition, LTPO is applicable to a display panel with a size midway between the case of using LTPS transistors and the case of using OS transistors (typically, a diagonal size greater than or equal to 1 inch and less than or equal to 50 inches).
Next, a cross-sectional view of the light-emitting and light-receiving apparatus is shown.
In
Each pixel circuit (e.g., the pixel circuit 530X(i, j) and the pixel circuit 530S(i, j) in
As the second substrate 770, a substrate where touch sensors are arranged in a matrix can be used. For example, a substrate provided with capacitive touch sensors or optical touch sensors can be used as the second substrate 770. Thus, the light-emitting and light receiving apparatus of one embodiment of the present invention can be used as a touch panel.
Note that the structure described in this embodiment can be used in an appropriate combination with any of the structures described in the other embodiments.
In this embodiment, electronic appliances of embodiments of the present invention will be described with reference to
An electronic appliance 5200B described in this embodiment includes an arithmetic device 5210 and an input/output device 5220 (see
The arithmetic device 5210 has a function of being supplied with operation data and has a function of supplying image data on the basis of the operation data.
The input/output device 5220 includes a display portion 5230, an input portion 5240, a detecting portion 5250, and a communication portion 5290 and has a function of supplying operation data and a function of being supplied with image data. The input/output device 5220 also has a function of supplying detection data, a function of supplying communication data, and a function of being supplied with communication data.
The input portion 5240 has a function of supplying operation data. For example, the input portion 5240 supplies operation data on the basis of operation by a user of the electronic appliance 5200B.
Specifically, a keyboard, a hardware button, a pointing device, a touch sensor, an illuminance sensor, an imaging device, an audio input device, an eye-gaze input device, an attitude detection device, or the like can be used as the input portion 5240.
The display portion 5230 includes a display panel and has a function of displaying image data. For example, the display panel described in Embodiment 3 can be used for the display portion 5230.
The detecting portion 5250 has a function of supplying detection data. For example, the detecting portion 5250 has a function of detecting a surrounding environment where the electronic appliance is used and supplying detection data.
Specifically, an illuminance sensor, an imaging device, an attitude detection device, a pressure sensor, a human motion sensor, or the like can be used as the detecting portion 5250.
The communication portion 5290 has a function of being supplied with communication data and a function of supplying communication data. For example, the communication portion 5290 has a function of being connected to another electronic appliance or a communication network through wireless communication or wired communication. Specifically, the communication portion 5290 has a function of wireless local area network communication, telephone communication, near field communication, or the like.
For example, the display can be performed on the display portion 5230 using an image signal received from another electronic appliance. When the electronic appliance is placed on a stand or the like, the display portion 5230 can be used as a sub-display. Thus, for example, a tablet computer can display an image so that the tablet computer can be suitably used even in an environment under strong external light, e.g., outdoors in fine weather.
Note that this embodiment can be combined with any of the other embodiments described in this specification as appropriate.
In this embodiment, a structure where the light-emitting device described in Embodiment 2 is used for a lighting device will be described with reference to
In the lighting device in this embodiment, a first electrode 401 is formed over a substrate 400 which is a support and has a light-transmitting property. The first electrode 401 corresponds to the first electrode 101 in Embodiment 2. In the case where light emission is extracted from the first electrode 401 side, the first electrode 401 is formed using a material having a light-transmitting property.
A pad 412 for supplying a voltage to a second electrode 404 is formed over the substrate 400.
An EL layer 403 is formed over the first electrode 401. The structure of the EL layer 403 corresponds to, for example, the structure of the EL layer 103 in Embodiment 2. Note that for these structures, the corresponding description can be referred to.
The second electrode 404 is formed to cover the EL layer 403. The second electrode 404 corresponds to the second electrode 102 in Embodiment 2. In the case where light-emission is extracted from the first electrode 401 side, the second electrode 404 is formed using a material having high reflectivity. The second electrode 404 is supplied with a voltage when connected to the pad 412.
As described above, the lighting device described in this embodiment includes a light-emitting device including the first electrode 401, the EL layer 403, and the second electrode 404. Since the light-emitting device is a light-emitting device with a high emission efficiency, the lighting device in this embodiment can be a lighting device with low power consumption.
The substrate 400 over which the light-emitting device having the above structure is formed is fixed to a sealing substrate 407 with sealants (405 and 406) and sealing is performed, whereby the lighting device is completed. It is possible to use only either the sealant 405 or the sealant 406. In addition, the inner sealant 406 (not illustrated in
When parts of the pad 412 and the first electrode 401 are provided to extend to the outside of the sealants 405 and 406, those can serve as external input terminals. An IC chip 420 mounted with a converter or the like, for example, may be provided over the external input terminals.
In this embodiment, application examples of lighting devices fabricated using the light-emitting apparatus of one embodiment of the present invention or the light-emitting device, which is part of the light-emitting apparatus, will be described with reference to
A ceiling light 8001 can be used as an indoor lighting device. Examples of the ceiling light 8001 include a direct-mount light and an embedded light. Such lighting devices are fabricated using the light-emitting apparatus and a housing or a cover in combination. Other than that, application to a cord pendant light (light that is suspended from the ceiling by a cord) is also possible.
A foot light 8002 lights the floor so that safety on the floor can be improved. It can be effectively used in a bedroom, on a staircase, or in a passage, for example. In that case, the size or shape of the foot light can be changed in accordance with the area or structure of a room. The foot light can be a stationary lighting device made from the combination of the light-emitting apparatus and a support.
A sheet-like lighting 8003 is a thin sheet-like lighting device. The sheet-like lighting, which is attached to a wall when used, is space-saving and thus can be used for a wide variety of applications. Furthermore, the area of the sheet-like lighting can be easily increased. The sheet-like lighting can also be used on a wall or housing having a curved surface, for example.
In addition, a lighting device 8004 in which the light from a light source is controlled to be only in a desired direction can be used.
A desk lamp 8005 includes a light source 8006. As the light source 8006, the light-emitting apparatus of one embodiment of the present invention or the light-emitting device, which is part of the light-emitting apparatus, can be used.
In addition to the above examples, when the light-emitting apparatus of one embodiment of the present invention or the light-emitting device, which is part of the light-emitting apparatus, is used as a part of furniture in a room, a lighting device with functions of furniture can be obtained.
As described above, a variety of lighting devices that include the light-emitting apparatus can be obtained. Note that these lighting devices are also embodiments of the present invention.
The structures described in this embodiment can be used in an appropriate combination with any of the structures described in the other embodiments.
This embodiment will describe a light-emitting and light-receiving apparatus 810 that is illustrated in
The light-emitting device 805a has a function of emitting light (hereinafter also referred to as a light-emitting function). The light-emitting device 805a includes an electrode 801a, an EL layer 803a, and an electrode 802. The light-emitting device 805a is preferably a light-emitting device utilizing organic EL (an organic EL device) described in Embodiment 2. The EL layer 803a interposed between the electrode 801a and the electrode 802 includes at least a light-emitting layer. The light-emitting layer contains a light-emitting substance. The EL layer 803a emits light when voltage is applied between the electrode 801a and the electrode 802. The EL layer 803a may include any of a variety of layers such as a hole-injection layer, a hole-transport layer, an electron-transport layer, an electron-injection layer, a carrier-blocking (hole-blocking or electron-blocking) layer, and a charge-generation layer, in addition to the light-emitting layer.
The light-receiving device 805b has a function of detecting light (hereinafter also referred to as a light-receiving function). For example, a pn or pin photodiode can be used as the light-receiving device 805b. The light-receiving device 805b includes an electrode 801b, a light-receiving layer 803b, and the electrode 802. The light-receiving layer 803b interposed between the electrode 801b and the electrode 802 includes at least an active layer. Note that for the light-receiving layer 803b, any of materials that are used for the variety of layers (e.g., the hole-injection layer, the hole-transport layer, the light-emitting layer, the electron-transport layer, the electron-injection layer, the carrier-blocking (hole-blocking or electron-blocking) layer, and the charge-generation layer) included in the above-described EL layer 803a can be used. The light-receiving device 805b functions as a photoelectric conversion device and generates charge on the basis of incident light on the light-receiving layer 803b, and the charge can be extracted as a current. At this time, voltage may be applied between the electrode 801b and the electrode 802. The amount of generated charge is determined depending on the amount of light incident on the light-receiving layer 803b.
The light-receiving device 805b has a function of detecting visible light. The light-receiving device 805b has sensitivity to visible light. The light-receiving device 805b further preferably has a function of detecting visible light and infrared light. The light-receiving device 805b preferably has sensitivity to visible light and infrared light.
In this specification and the like, a blue (B) wavelength range is greater than or equal to 400 nm and less than 490 nm, and blue (B) light has at least one emission spectrum peak in the wavelength range. A green (G) wavelength range is greater than or equal to 490 nm and less than 580 nm, and green (G) light has at least one emission spectrum peak in the wavelength range. A red (R) wavelength range is greater than or equal to 580 nm and less than 700 nm, and red (R) light has at least one emission spectrum peak in the wavelength range. In this specification and the like, a visible light wavelength is greater than or equal to 400 nm and less than 700 nm, and visible light has at least one emission spectrum peak in the wavelength range. An infrared (IR) wavelength range is greater than or equal to 700 nm and less than 900 nm, and infrared (IR) light has at least one emission spectrum peak in the wavelength range.
The active layer of the light-receiving device 805b contains a semiconductor. Examples of the semiconductor include an inorganic semiconductor such as silicon and an organic semiconductor including an organic compound. As the light-receiving device 805b, an organic semiconductor device (or an organic photodiode) including an organic semiconductor in the active layer is preferably used. An organic photodiode, which is easily made thin, lightweight, and large in area and has high flexibility in shape and design, can be employed for a variety of display apparatuses. With use of an organic semiconductor, the EL layer 803a included in the light-emitting device 805a and the light-receiving layer 803b included in the light-receiving device 805b can be formed by the same method (e.g., a vacuum evaporation method) with the same manufacturing apparatus, which is preferable. Note that the organic compound of one embodiment of the present invention can be used for the light-receiving layer 803b in the light-receiving device 805b.
In the display apparatus of one embodiment of the present invention, an organic EL device can be suitably used as the light-emitting device 805a and an organic photodiode can be suitably used as the light-receiving device 805b. The organic EL device and the organic photodiode can be formed over the same substrate. Thus, the organic photodiode can be incorporated in the display apparatus using the organic EL device. The display apparatus of one embodiment of the present invention has one or both of an image capturing function and a sensing function in addition to an image displaying function.
The electrode 801a and the electrode 801b are provided on the same plane. In
As the substrate 800, a substrate having heat resistance high enough to withstand the formation of the light-emitting device 805a and the light-receiving device 805b can be used. When an insulating substrate is used as the substrate 800, a glass substrate, a quartz substrate, a sapphire substrate, a ceramic substrate, an organic resin substrate, or the like can be used. Alternatively, a single crystal semiconductor substrate or a polycrystalline semiconductor substrate using silicon or silicon carbide as a material, a compound semiconductor substrate of silicon germanium or the like, or a semiconductor substrate such as an SOI substrate can be used.
As the substrate 800, it is particularly preferable to use the above-described insulating substrate or semiconductor substrate where a semiconductor circuit including a semiconductor element such as a transistor is formed. The semiconductor circuit preferably forms a pixel circuit, a gate line driver circuit (a gate driver), a source line driver circuit (a source driver), or the like. In addition to the above, an arithmetic circuit, a memory circuit, or the like may be formed.
The electrode 802 is formed of a layer shared by the light-emitting device 805a and the light-receiving device 805b. A conductive film transmitting visible light and infrared light is used as the electrode through which light exits or enters among these electrodes. A conductive film reflecting visible light and infrared light is preferably used as the electrode through which light neither exits nor enters.
The electrode 802 in the display apparatus of one embodiment of the present invention functions as one of the electrodes in each of the light-emitting device 805a and the light-receiving device 805b.
In
In the structure illustrated in
In the structure illustrated in
With the common layer 806 and the common layer 807, a light-receiving device can be incorporated without a significant increase in the number of times of separate formation of devices, whereby the light-emitting and light-receiving apparatus 810A can be manufactured with a high throughput.
An optimum material for forming the light-emitting device 805a is selected for the layer 806a and the layer 807a and an optimum material for forming the light-receiving device 805b is selected for the layer 806b and the layer 807b, whereby the light-emitting device 805a and the light-receiving device 805b can have higher performance in the light-emitting and light-receiving apparatus 810B.
Note that the light-receiving devices 805b described in this embodiment can be arranged at a resolution higher than or equal to 100 ppi, preferably higher than or equal to 200 ppi, more preferably higher than or equal to 300 ppi, further preferably higher than or equal to 400 ppi, still further preferably higher than or equal to 500 ppi and lower than or equal to 2000 ppi, lower than or equal to 1000 ppi, or lower than or equal to 600 ppi, for example. In particular, when the light-receiving devices 805b are arranged at a resolution higher than or equal to 200 ppi and lower than or equal to 600 ppi, preferably higher than or equal to 300 ppi and lower than or equal to 600 ppi, the light-receiving devices can be suitably used for image capturing of a fingerprint. In the case where fingerprint authentication is performed with the display apparatus of one embodiment of the present invention, the increased resolution of the light-receiving devices 805b enables, for example, highly accurate extraction of the minutiae of fingerprints; thus, the accuracy of the fingerprint authentication can be increased. The resolution is preferably higher than or equal to 500 ppi, in which case the authentication conforms to the standard by the National Institute of Standards and Technology (NIST) or the like. On the assumption that the resolution at which the light-receiving devices are arranged is 500 ppi, the size of each pixel is 50.8 μm, which indicates that the resolution is adequate for image capturing of a fingerprint ridge distance (typically, greater than or equal to 300 μm and less than or equal to 500 μm).
The structures described in this embodiment can be used in an appropriate combination with any of the structures described in the other embodiments.
This synthesis example specifically describes a method for synthesizing 2-[3-(dibenzo[f,h]quinoxalin-2-yl)-5-(9-phenanthren-9-yl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: Pn-mDBqPTzn) shown as Structural Formula (100) in Embodiment 1.
Step 1 was performed in the following manner. The synthesis scheme is shown in Formula (A-1).
First, into a 200-mL three-neck flask were put 5.1 g (12 mmol) of 2-(3-bromo-5-chlorophenyl)-4,6-diphenyl-1,3,5-triazine, 2.7 g (12 mmol) of 9-phenanthrene boronic acid, 4.0 g (29 mmol) of potassium carbonate (abbreviation: K2CO3), 70 mL of toluene, 10 mL of ethanol, and 10 mL of water. Then, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. Next, the mixture was heated to 70° C. under a nitrogen stream, 0.42 g (0.60 mmol) of bis(triphenylphosphine)palladium(II) dichloride (abbreviation: Pd(PPh3)2Cl2) was added, the temperature was increased to 90° C., and the mixture was stirred and refluxed for 4 hours. After the reaction, water was added to the mixture and suction filtration was performed, and the residue was washed with water and ethanol. Toluene was added to the obtained residue and heating was performed for dissolution, followed by filtration through Celite and alumina. The obtained filtrate was concentrated and dried to give 5.0 g of a white solid (in a yield of 79%).
Step 2 was performed in the following manner. The synthesis scheme is shown in Formula (A-2).
First, into a 200-mL three-neck flask were put 2.6 g (4.9 mmol) of 2-[3-chloro-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine obtained in Step 1, 1.9 g (7.4 mmol) of bis(pinacolato)diboron, 1.4 g (15 mmol) of potassium acetate (abbreviation: KOAc), 47 mg (10 μmol) of 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl (abbreviation; Xphos), and 50 mL of 1,4-dioxane. Next, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. After that, the inside of the flask was heated to 70° C. under a nitrogen stream, 11 mg (50 μmol) of palladium acetate (abbreviation: Pd(OAc)2) was added, the temperature was increased to 100° C., and the mixture was stirred and refluxed for 9 hours. After the reaction, the mixture was suction-filtered, and the obtained filtrate was subjected to extraction using ethyl acetate and washed with water. The obtained organic layer was washed with saturated saline, dried using magnesium sulfate, and then concentrated to give 2.4 g of a white solid (in a yield of 80%).
Step 3 was performed in the following manner. The synthesis scheme is shown in Formula (A-2).
First, into a 200-mL three-neck flask were put 0.83 g (3.1 mmol) of 2-chloro-dibenzoquinoxaline, 1.9 g (3.1 mmol) of the compound obtained in Step 2, 1.0 g (7.2 mmol) of potassium carbonate, 0.10 g (0.33 mmol) of tris(2-methylphenyl)phosphine (abbreviation: P (o-tolyl)3), 40 mL of toluene, 5 mL of ethanol, and 5 mL of water. Next, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. After that, the mixture was heated to 70° C. under a nitrogen stream, 15 mg (70 μmol) of palladium acetate was added, the temperature was increased to 90° C., and the mixture was stirred and refluxed for 2.5 hours. After the reaction, the mixture was suction-filtered, and the obtained residue was washed with water and ethanol. Toluene was added to the obtained residue and heating was performed at 50° C., and then suction filtration was performed. The obtained residue was concentrated and dried to give 2.0 g of a white solid (in a yield of 90%).
Purification by a train sublimation method was performed by heating 2.0 g of the obtained white solid at 360° C. under a pressure of 2.8 Pa with an argon flow rate of 15 mL/min for 14 hours, so that 1.0 g of a white solid was obtained (in a collection rate of 50%).
The results of analysis by nuclear magnetic resonance spectroscopy (1H-NMR) performed on the obtained white solid in a deuterated 1,1,2,2-tetrachloroethane (abbreviation: TCE-d2) solution are shown below.
1H-NMR (TCE-d2, 500 MHz): δ=7.60-7.86 (m, 14H), 7.99 (s, 1H), 8.05 (dd, 2H), 8.67 (d, 2H), 8.81-8.89 (m, 7H), 9.09 (s, 1H), 9.27 (d, 1H), 9.44 (d, 1H), 9.72 (s, 1H), 9.86 (s, 1H).
The absorption spectrum and emission spectrum of Pn-mDBqPTzn were measured. The absorption spectrum was measured with an ultraviolet-visible spectrophotometer (U-4100 produced by Hitachi, Ltd.). The emission spectrum was measured with a fluorescence spectrophotometer (FP-8600, produced by JASCO Corporation).
As shown in
The glass transition temperature (Tg) of Pn-mDBqPTzn was measured. The Tg was measured with a differential scanning calorimeter (PYRIS 1 DSC produced by PerkinElmer Japan Co., Ltd.) while a powder was put on an aluminum cell. As a result, the Tg of Pn-mDBqPTzn was 161° C. This reveals that the compound of the present invention exhibits an excellent thermal property and the thin film formed using such a compound is expected to have stable film quality. The use of the compound capable of forming a thin film with stable quality allows a highly heat-resistant organic device to be provided.
In an organic device such as a light-emitting device or a light-receiving device, a layer provided in a higher position preferably has higher resistance (heat resistance, film quality stability, or the like). This is because a layer provided in a higher position might be influenced more greatly by the formation process of the organic device. For example, when used for an electron-transport layer, the compound of the present application desirably has a Tg higher than that of a host material in a light-emitting layer in a lower position by 5° C. or more, further preferably 10° C. or more. It is also effective to make the Tg higher than that of a material for a hole-transport layer or a hole-injection layer that is in a lower position by 5° C. or more, preferably 10° C. or more. A layer (an electron-transport layer such as a hole-blocking layer) may be provided between the light-emitting layer and the electron-transport layer, and also in this case, the Tg of the electron-transport layer is preferably made higher than that of the hole-blocking layer.
The HOMO level and the LUMO level of Pn-mDBqPTzn were calculated on the basis of cyclic voltammetry (CV) measurement. The calculation method is shown below.
An electrochemical analyzer (model number: ALS model 600A or 600C, produced by BAS Inc.) was used as a measurement apparatus. To prepare a solution for the CV measurement, dehydrated dimethylformamide (DMF) (produced by Sigma-Aldrich Inc., 99.8%, catalog No. 22705-6) was used as a solvent, tetra-n-butylammonium perchlorate (n-Bu4NClO4) (produced by Tokyo Chemical Industry Co., Ltd., catalog No. T0836) as a supporting electrolyte was dissolved at a concentration of 100 mmol/L, and the object to be measured was dissolved at a concentration of 2 mmol/L.
A platinum electrode (PTE platinum electrode, produced by BAS Inc.) was used as a working electrode, another platinum electrode (Pt counter electrode for VC-3 (5 cm), produced by BAS Inc.) was used as an auxiliary electrode, and an Ag/Ag+ electrode (RE7 reference electrode for a non-aqueous solvent, produced by BAS Inc.) was used as a reference electrode. Note that the measurement was performed at room temperature (higher than or equal to 20° C. and lower than or equal to 25° C.).
The scan speed in the CV measurement was fixed to 0.1 V/see, and an oxidation potential Ea [V] and a reduction potential Ec [V] with respect to the reference electrode were measured. Ea is an intermediate potential of an oxidation-reduction wave, and Ec is an intermediate potential of a reduction-oxidation wave. Here, since the potential energy of the reference electrode used in this example with respect to the vacuum level is known to be −4.94 [eV], the HOMO level and the LUMO level can be calculated by the following formulae: HOMO level [eV]=−4.94−Ea and LUMO level [eV]=−4.94−Ec.
Furthermore, CV measurement was repeated 100 times, and the oxidation-reduction wave in the hundredth cycle was compared with the oxidation-reduction wave in the first cycle to examine the electrical stability of the compound.
From the results, the oxidation potential Ea [V] of Pn-mDBqPTzn was found to be less than the lower measurement limit of the apparatus, and the HOMO level can be estimated to be lower than or equal to −6.4 eV. Meanwhile, from the measurement results of the reduction potential Ec [V], the LUMO level was found to be −3.04 eV.
According to the results of the LUMO level, it can be considered that electrons can be suitably donated and accepted, and Pn-mDBqPTzn can be suitably used for an electron-transport layer and a light-emitting layer of an organic device and a charge-generation layer of a tandem element.
In the case where Pn-mDBqPTzn is used for an electron-transport layer of an organic device, the LUMO level of an electron-transport layer material is preferably lower than the LUMO level of a host material in a light-emitting layer. In addition, the LUMO level of the electron-transport layer material is preferably lower than the LUMO level of a cap layer material. It is particularly preferable that the LUMO levels satisfy the relation of the cap layer material >the host material in the light-emitting layer >the electron-transport layer material. In the case where a plurality of light-emitting devices (e.g., a red device, a blue device, and a green device) are included, each of the light-emitting devices preferably satisfies the relation of the LUMO levels.
The refractive index of Pn-mDBqPTzn was measured with a spectroscopic ellipsometer (M-2000U produced by J. A. Woollam Japan Corp.). For the measurement, a film formed by depositing Pn-mDBqPTzn to a thickness of approximately 50 nm over a quartz substrate by a vacuum evaporation method was used. At a wavelength of 633 nm, the ordinary refractive index n Ordinary (no) was 1.85. The results show that Pn-mDBqPTzn can be effectively used as the host material, the hole-transport material, the electron-transport material, or the material for the cap layer provided over the cathode. In the case where is used as the material for the cap layer, the refractive index is preferably higher than or equal to 1.75 and lower than or equal to 2.50.
In the case where Pn-mDBqPTzn is used as a hole-transport material or an electron-transport material, lowering the refractive index can further increase the emission efficiency. An example of a method for lowering the refractive index is adding an alkyl group as a substituent to the compound of the present application, by which the refractive index can be adjusted to higher than or equal to 1.50 and lower than or equal to 1.85. For example, in the case of General Formulae (G1) to (G4), at least one of R1 to R4 preferably includes an alkyl group.
When used as the host material, the hole-transport layer material, or the electron-transport layer material, the compound of the present application preferably has a refractive index lower than that of the cap layer material or the host material in the light-emitting layer. Specifically, the refractive index of the compound of the present application is lower than the refractive index of the cap layer preferably by 0.1 or more, further preferably by 0.2 or more. Furthermore, the refractive index of the compound of the present application is lower than the refractive index of the host material in the light-emitting layer preferably by 0.1 or more, further preferably by 0.2 or more. In particular, in the case where Pn-mDBqPTzn is used as the electron-transport layer material, making the refractive index lower than those of the cap layer and the light-emitting layer can increase the emission efficiency.
This synthesis example describes a method for synthesizing 2-[3-(2,6-dimethyl-3-pyridinyl)-5-(9-phenanthrenyl)phenyl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mPn-mDMePyPTzn), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (160).
Note that mPn-mDMePyPTzn was manufactured in a manner similar to that of Synthesis example 1 except that 3-bromo-2,6-dimethylpyridine was used instead of 2-chloro-dibenzoquinoxaline in Step 3 of Synthesis example 1. The synthesis scheme is shown in Formula (B-1). Note that the heating time was 5 hours and the heating temperature was 65° C.
The absorption spectrum and emission spectrum of a light-emitting device containing mPn-mDMePyPTzn were measured in a manner similar to that of Example 1. In a solution state, the peak wavelengths of the absorption spectrum were 256 nm and 350 nm, and the peak wavelength of the emission spectrum was 436 nm. In a thin film state, the peak wavelength of the absorption spectrum was 336 nm, and the peak wavelength of the emission spectrum was 409 nm (excitation wavelength: 310 nm).
The Tg of mPn-mDMePyPTzn, which was measured in a manner similar to that of Example 1, was 121° C.
This synthesis example describes a method for synthesizing 2-[(1,1′-biphenyl)-4-yl]-4-phenyl-6-[9,9′-spirobi (9H-fluoren)-2-yl]-1,3,5-triazine (abbreviation: BP-SFTzn), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (440). The synthesis scheme is shown in Formula (C-1).
Into a 200-mL three-neck flask were put 1.7 g (4.8 mmol) of 2-(biphenyl-4-yl)-4-chloro-6-phenyl-1,3,5-triazine), 2.1 g (5.8 mmol) of 9,9′-spirobi[9H-fluorene]-2-boronic acid), 1.6 g (12 mmol) of potassium carbonate, 50 mL of toluene, 7 mL of ethanol, and 7 mL of water. Next, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. After that, the inside of the flask was heated to 70° C. under a nitrogen stream, 0.20 g (0.29 mmol) of bis(triphenylphosphine)palladium(II) dichloride was added, the temperature was increased to 90° C., and the mixture was stirred and refluxed for 10 hours. Toluene and water were added to a reactant and an organic layer was extracted. The obtained organic layer was dried using magnesium sulfate and naturally filtered, and the obtained filtrate was concentrated to give a solid. The obtained solid was purified by silica gel column chromatography (toluene:hexane=1:1 in a developing solvent). The obtained solid was recrystallized with toluene and hexane, whereby 2.7 g of a white solid, which is a target compound BP-SFTzn, was obtained (in a yield of 90%).
The absorption spectrum and emission spectrum of BP-SFTzn were measured. In the measurement of a solution state, toluene was used as a solvent. Except for the above, the measurement was performed in a manner similar to that of Example 1. In the solution state, the peak wavelength of the absorption spectrum was 358 nm, and the peak wavelength of the emission spectrum was 388 nm. In a thin film state, the peak wavelength of the absorption spectrum was 352 nm, and the peak wavelength of the emission spectrum was 419 nm.
The Tg of BP-SFTzn, which was measured in a manner similar to that of Example 1, was 148° C.
This synthesis example describes a method for synthesizing 2-[(1,1′-biphenyl)-4-yl]-4-phenyl-6-{(3′,5′-di-tert-butyl)-1,1′-biphenyl-3-yl}-1,3,5-triazine (abbreviation: BP-SF(4)Tzn), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (434).
Note that BP-SF(4)Tzn was manufactured in a manner similar to that of Synthesis example 3 except that 2-(9,9′-spirobi[9H-fluoren]-4-yl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane) was used instead of 9,9′-spirobi[9H-fluorene]-2-boronic acid) in Synthesis example 3. The synthesis scheme is shown in Formula (D-1). Note that the heating time was 4.5 hours and the heating temperature was 90° C.
The absorption spectrum and emission spectrum of a light-emitting device containing BP-SF(4)Tzn were measured in a manner similar to that of Example 3. In a solution state, the peak wavelength of the absorption spectrum was 331 nm, and the peak wavelength of the emission spectrum was 423 nm. In a thin film state, the peak wavelength of the absorption spectrum was 357 nm, and the peak wavelength of the emission spectrum was 415 nm.
The Tg of BP-SF(4)Tzn, which was measured in a manner similar to that of Example 1, was 148° C.
This synthesis example describes a method for synthesizing 2,4-bis[4-(1-naphthyl)phenyl]-6-[4-(3-pyridyl)phenyl]pyrimidine (abbreviation: 2,4NP-6PyPPm), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (424).
Into a 200-mL three-neck flask were put 1.1 g (5.8 mmol) of 2,4,6-trichloropyrimidine, 1.2 g (5.8 mmol) of 4-(3-pyridyl)phenylboronic acid, 8.0 g (58 mmol) of potassium carbonate, 80 mL of 1,4-dioxane, and 30 mL of water, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. Next, the inside of the flask was heated to 40 under a nitrogen stream, 0.20 g (0.29 mmol) of bis(triphenylphosphine)palladium(II) dichloride was added, and stirring was performed for 6.5 hours, so that a reactant containing 4-[4-(3-pyridinyl)phenyl]-2,6-dichloropyrimidine was obtained. Then, 3.3 g (13 mmol) of 4-(1-naphthyl)phenylboronic acid was added to the reactant containing 4-[4-(3-pyridinyl)phenyl]-2,6-dichloropyrimidine, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. After that, the inside of the flask was heated to 80° C., 0.20 g (0.29 mmol) of bis(triphenylphosphine)palladium(II) dichloride was added, and stirring was performed for 6 hours. Next, ethyl acetate and water were added to a reactant, and an organic layer was extracted. The obtained organic layer was dried using magnesium sulfate and naturally filtered, and the obtained filtrate was concentrated to give a solid. The obtained solid was purified by silica gel column chromatography (toluene:ethyl acetate=2:1 in a developing solvent). The obtained compound was recrystallized with toluene, whereby 2.2 g of a pale yellow solid was obtained (in a yield of 60%). The synthesis scheme is shown in Formula (E-1).
The synthesis was performed in one step in Formula (E-1), but can be performed in two steps. In that case, the reactant containing 4-[4-(3-pyridinyl)phenyl]-2,6-dichloropyrimidine is purified (e.g., filtered) to obtain the 4-[4-(3-pyridinyl)phenyl]-2,6-dichloropyrimidine, and then coupling reaction with 4-(1-naphthyl)phenylboronic acid is performed to obtain a target substance (2,4NP-6PyPPm).
The absorption spectrum and emission spectrum of 2,4NP-6PyPPm were measured in a manner similar to that of Example 3. In a solution state, the peak wavelength of the absorption spectrum was 320 nm, and the peak wavelength of the emission spectrum was 387 nm. In a thin film state, the peak wavelength of the absorption spectrum was 311 nm, and the peak wavelength of the emission spectrum was 414 nm.
The Tg of 2,4NP-6PyPPm, which was measured in a manner similar to that of Example 1, was 119° C.
This synthesis example describes a method for synthesizing 4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenyl-6-(1,1′-biphenyl-4-yl)pyrimidine (abbreviation: 6BP-4Cz2PPm), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (404).
Into a 200-mL three-neck flask were put 2.9 g (8.3 mmol) of 4-(biphenyl-4-yl)-6-chloro-2-phenylpyrimidine, 4.5 g (10 mmol) of 3,5-di-9H-carbazol-9-ylphenylboronic acid, 2.8 g (20 mmol) of potassium carbonate, 80 mL of toluene, 12 mL of ethanol, and 12 mL of water, the mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. Next, the inside of the flask was heated to 70° C. under a nitrogen stream, 0.35 g (50 μmol) of bis(triphenylphosphine)palladium(II) dichloride was added, the temperature was increased to 90° C., and the mixture was stirred and refluxed for 6 hours. Water was added to a reactant, the obtained mixture was suction-filtered, and a residue was washed with ethanol and water. The obtained residue was dissolved in toluene by heating, the obtained solution was filtered through Celite and aluminum oxide, and the filtrate was concentrated to give a solid. The obtained solid was recrystallized with toluene, whereby 5.4 g of a white solid was obtained (in a yield of 90%). The synthesis scheme is shown in Formula (F-1).
The absorption spectrum and emission spectrum of 6BP-4Cz2PPm were measured in a manner similar to that of Example 1. In a solution state, the peak wavelength of the absorption spectrum was 296 nm, and the peak wavelength of the emission spectrum was 423 nm. In a thin film state, the peak wavelength of the absorption spectrum was 366 nm, and the peak wavelength of the emission spectrum was 425 nm.
This synthesis example describes a method for synthesizing 6-(1,1′-biphenyl-3-yl)-4-[3,5-bis(9H-carbazol-9-yl)phenyl]-2-phenylpyrimidine (abbreviation: 6mBP-4Cz2PPm), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (405).
Note that 6mBP-4Cz2PPm was manufactured in a manner similar to that of Synthesis example 6 except that 4-(biphenyl-3-yl)-6-chloro-2-phenylpyrimidine was used instead of 4-(biphenyl-4-yl)-6-chloro-2-phenylpyrimidine in Synthesis example 6. Note that the heating time was 11 hours and the heating temperature was 90° C. The synthesis scheme is shown in General Formula (G-1).
The absorption spectrum and emission spectrum of 6mBP-4Cz2PPm were measured in a manner similar to that of Example 1. In a solution state, the peak wavelength of the absorption spectrum was 338 nm, and the peak wavelength of the emission spectrum was 423 nm. In a thin film state, the peak wavelength of the absorption spectrum was 3356 nm, and the peak wavelength of the emission spectrum was 423 nm.
The Tg of 6mBP-4Cz2PPm, which was measured in a manner similar to that of Example 1, was 132° C.
This synthesis example describes a method for synthesizing 2-[3′-(9,9-dimethyl-9H-fluoren-2-yl)biphenyl-3-yl]-4,6-diphenyl-1,3,5-triazine (abbreviation: mFBPTzn), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (409).
Into a 1-L three-neck flask were put 15 g (36 mmol) of 2-(3′-chlorobiphenyl-3-yl)-4,6-diphenyl-1,3,5-triazine, 9.1 g (38 mmol) of 9,9-dimethyl-9Hfluorene-2-boronic acid, 0.77 mg (2.1 mmol) of di(1-adamantyl)-n-butylphosphine (another name: cataCXium (registered trademark) A) (abbreviation: cataCXium), 18 g (86 mmol) of tripotassium phosphate (abbreviation: K3PO4), and 185 mL of diethylene glycol dimethyl ether (abbreviation: diglyme). Next, this mixture was degassed by being stirred under reduced pressure, and the air in the flask was replaced with nitrogen. After that, the inside of the flask was heated to 80° C. under a nitrogen stream, 0.24 mg (1.1 mmol) of palladium acetate was added, the temperature was increased to 140° C., and the mixture was stirred and refluxed for 7 hours. Furthermore, 0.51 g (1.4 mmol) of cataCXium and 0.17 mg (0.75 mmol) of palladium acetate were added, and the mixture was stirred and refluxed at 150° C. for 8 hours. A reactant was dissolved in toluene, filtration through Celite and aluminum oxide was performed, and the obtained filtrate was concentrated to give a solid. The obtained solid was purified by silica gel column chromatography (toluene:hexane=2:3 in a developing solvent). The obtained solid was recrystallized with toluene and hexane, whereby 13 g of a white solid, which is a target compound mFBPTzn, was obtained (64%). The synthesis scheme is shown in Formula (H-1).
The absorption spectrum and emission spectrum of mFBPTzn were measured in a manner similar that of Example 1. In a solution state, the peak wavelength of the absorption spectrum was 315 nm, and the peak wavelength of the emission spectrum was 471 nm. In a thin film state, the peak wavelength of the absorption spectrum was 317 nm, and the peak wavelength of the emission spectrum was 410 nm.
The Tg of mFBPTzn, which was measured in a manner similar to that of Example 1, was 95° C.
This synthesis example describes a method for synthesizing 3-[9-(4,6-diphenyl-1,3,5-triazin-2-yl)-2-dibenzofuranyl]-9-phenyl-9H-carbazole (abbreviation: PCDBfTzn), which is an organic compound usable as a material that can be contained in an organic device (e.g., an electron-transport material and a host material), and is represented by Structural Formula (445).
Into a three-neck flask were put 2.0 g (4.7 mmol) of 2-(8-chloro-1-dibenzofuranyl)-4,6-diphenyl-1,3,5-triazine, 1.6 g (5.6 mmol) of 9-phenyl-9H-carbazole-3-boronic acid, 85 mg (0.23 mmol) of di(1-adamantyl)-n-butylphosphine, and 3.0 g (14 mmol) of tripotassium phosphate. Next, the air in the flask was replaced with nitrogen, 30 mL of diethylene glycol dimethyl ether was added, and the mixture was degassed by being stirred under reduced pressure. After that, the inside of the flask was heated to 80° C., 18 mg (80 μmol) of palladium acetate was added, the temperature was increased to 120° C., and the mixture was stirred and refluxed for 14 hours. Furthermore, 50 mg (0.14 mmol) of di(1-adamantyl)-n-butylphosphine and 15 mg (70 μmol) of palladium acetate were added, and the mixture was stirred and refluxed at 140° C. for 12 hours. A reactant was suction-filtered, and the obtained residue was washed with toluene and water. The obtained residue was dissolved in toluene by heating, the obtained solution was filtered through Celite and aluminum oxide, and the obtained filtrate was concentrated to give a solid. The obtained solid was recrystallized with toluene, whereby 1.4 g of a yellow solid was obtained (in a yield of 45%). The synthesis method is shown in Formula (I-1).
The absorption spectrum and emission spectrum of PCDBfTzn were measured in a manner similar to that of Example 1. In a thin film state, the peak wavelength of the absorption spectrum was 395 nm, and the peak wavelength of the emission spectrum was 500 nm.
The Tg of PCDBfTzn, which was measured in a manner similar to that of example 1, was 116° C.
Although the details are omitted, Structures (100) to (450) and the like described in Embodiment 1 can be manufactured in a manner similar to those of Examples 1 to 9. In this case, the structures can be manufactured by the method described in Synthesis Methods (a-1) to (a-5) or (b-1) with the use of a compound including any of the substituents (R-01) to (R-112) (a halogen, a boronic acid, or the like) described in Embodiment 1 as appropriate.
This example describes light-emitting devices of embodiments of the present invention described in the embodiments and a comparative light-emitting device. Structural formulae of organic compounds used in the light-emitting devices of embodiments of the present invention are shown below.
First, indium tin oxide containing silicon oxide (ITSO) was deposited over a glass substrate by a sputtering method, so that a first electrode was formed. Note that the thickness was 70 nm and the area of the electrode was 2 mm×2 mm.
Next, in pretreatment for forming the light-emitting device over the substrate, a surface of the substrate was washed with water and baking was performed at 200° C. for one hour, and then UV ozone treatment was performed for 370 seconds.
After that, the substrate was transferred into a vacuum evaporation apparatus in which the pressure was reduced to about 1×10−4 Pa, vacuum baking at 170° C. for 30 minutes was performed in a heating chamber in the vacuum evaporation apparatus, and then the substrate was naturally cooled down for about 30 minutes.
Next, the substrate on which the first electrode was formed was fixed to a substrate holder provided in the vacuum evaporation apparatus such that the surface on which the first electrode was formed faced downward, and BBABnf represented by Structural Formula (i) and OCHD-003 were co-evaporated over the first electrode in a weight ratio of 1:0.1(=BBABnf:OCHD-003) to a thickness of 10 nm by an evaporation method using resistance heating, so that a hole-injection layer was formed. Here, a substance containing halogen and having a mass number of 672 was used as OCHD-003 (also referred to as an electron-accepting substance).
Over the hole-injection layer, BBABnf represented by Structural Formula (i) was evaporated to a thickness of 20 nm, so that a first hole-transport layer was formed.
Over the first hole-transport layer, PCzN2 represented by Structural Formula (ii) was evaporated to a thickness of 10 nm, so that a second hole-transport layer was formed.
Over the second hole-transport layer, αN-βNPAnth (a material functioning as a host) represented by Structural Formula (iii) and 3,10PCA2Nbf(iv)-02 (a material functioning as a dopant) represented by Structural Formula (iv) were co-evaporated in a weight ratio of 1:0.015(=αN-βNPAnth: 3,10PCA2Nbf(iv)-02) to a thickness of 25 nm, so that a light-emitting layer was formed.
Over the light-emitting layer, 6mBP-4Cz2PPm represented by Structural Formula (v) was evaporated to a thickness of 10 nm, so that a first electron-transport layer was formed.
Over the first electron-transport layer, Pn-mDBqPTzn (Structural Formula (100)) of one embodiment of the present invention and Liq represented by Structural Formula (vi) were co-evaporated in a weight ratio of 1:1 to a thickness of 15 nm, so that a second electron-transport layer was formed.
Over the second electron-transport layer, Liq represented by Structural Formula (vi) was evaporated to a thickness of 1 nm, so that an electron-injection layer was formed.
After that, aluminum was evaporated over the electron-transport layer to a thickness of 200 nm to form a second electrode, whereby a light-emitting device 1 of this example was fabricated.
In a light-emitting device 2, mPn-mDMePyPTzn (Structural Formula (160)) of one embodiment of the present invention was used instead of Pn-mDBqPTzn in the second electron-transport layer of the light-emitting device 1.
Table 1 shows the element structures of the light-emitting device 1 and the light-emitting device 2 fabricated in the above manner.
These light-emitting devices were subjected to sealing with a glass substrate (a sealant was applied to surround the devices, followed by UV treatment and one-hour heat treatment at 80° C. at the time of sealing) in a glove box containing a nitrogen atmosphere so that the light-emitting devices were not exposed to the air. Then, the initial characteristics were measured.
Table 2 shows the main characteristics of the light-emitting device 1 and the light-emitting device 2 at approximately 1000 cd/m2. Luminance and CIE chromaticity were measured with a luminance colorimeter (BM-5A produced by TOPCON TECHNOHOUSE CORPORATION), and emission spectra were measured with a multi-channel spectrometer (PMA-11 produced by Hamamatsu Photonics K.K.). Note that the measurement of the light-emitting devices was performed at room temperature (in an atmosphere maintained at 23° C.).
Furthermore,
As shown in
The above element characteristics show that Pn-mDBqPTzn (Structural Formula (100)) and mPn-mDMePyPTzn (Structural Formula (160)) that are embodiments of the present invention are materials having excellent electron-transport properties and being particularly suitable as electron-transport layer materials of a light-emitting device.
This example describes reliability tests of the light-emitting device 1 and the light-emitting device 2 at high temperature.
As shown in
One factor of the excellent high-temperature resistance of Pn-mDBqPTzn (Structural Formula (100)) is the above-described high glass transition temperature Tg of 161° C. In contrast, the Tg of mPn-mDMePyPTzn (Structural Formula (160)) is 123° C.
Another possible factor of the excellent high-temperature resistance of Pn-mDBqPTzn (Structural Formula (100)) is that, when R3 has a molecular weight of 80 or more in General Formula (G1), which is a molecular structure of a compound of the present application, a thin film with more stable film quality can be obtained. Note that mPn-mDMePyPTzn used for the light-emitting device 2 is a pyridyl group having a molecular weight of 76 (excluding two methyl groups). In contrast, as to Pn-mDBqPTzn used for the light-emitting device 1, R3 in General Formula (G1) is dibenzo[f.h]quinoxaline, and the molecular weight of Pn-mDBqPTzn as a substituent is 229. These differences probably caused the difference in stability of film quality and driving lifetime at high temperature between the fabricated elements.
From the above, the glass transition temperature of a compound used for a light-emitting device is preferably higher than or equal to 130° C., further preferably higher than or equal to 140° C., still further preferably higher than or equal to 150° C., yet still further preferably higher than or equal to 160° C.
Another factor is the number of condensed rings in Pn-mDBqPTzn larger than that in mPn-mDMePyPTzn. Another factor is an increased molecular weight of the condensed rings. Another factor is an increased number of nitrogen atoms contained in the condensed rings.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-194181 | Nov 2021 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2022/061119 | 11/18/2022 | WO |
