Patent Application
20230157166
The present disclosure relates to an organic compound and an organic light-emitting element including the same.
The organic light-emitting element (hereafter also referred to as “organic electroluminescence element” or “organic EL element”) is an electronic element including a pair of electrodes and an organic compound layer disposed between the electrodes. An electron and a hole being injected from the pair of electrodes generates an exciton of a light-emitting organic compound in the organic compound layer, and the organic light-emitting element emits light when the exciton returns to a ground state. Recently, the organic light-emitting element has significantly progressed so as to enable a low driving voltage, diverse emission wavelengths, high speed responsiveness, and thickness reduction and weight reduction of a light-emitting apparatus to be realized.
In this regard, to date, creation of compounds suitable for the organic light-emitting element have been intensively performed. The reason for this is that creation of a compound having excellent element life characteristics is important for providing a high-performance organic light-emitting element. Regarding the compounds created until now, examples of the compound in which an end of a phenylene group in diphenyldiazatriphenylene is substituted with a condensed polycyclic group include Compound 1-A below which is described in US 2014/0034925.
According to examination of the present inventors, since Compound 1-A has small S1 (singlet energy) and has room for improvement in thermal properties, when Compound 1-A is used for the organic light-emitting element, an element life is short, and an organic light-emitting element having excellent durability characteristics is not obtained.
The present disclosure provides an organic compound having excellent element life characteristics when used for an organic light-emitting element. In addition, the present disclosure provides an organic light-emitting element having excellent life characteristics.
The organic compound according to the present disclosure is denoted by formula (1) below.
In formula (1), each of R1 to R8 is selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, and a cyano group.
A is a structure denoted by A below, * represents a position where bonding is performed.
In A above, B is selected from the group consisting of structures denoted by (B-1) to (B-15) below, * represents a position where bonding is performed.
In (B-1) to (B-15) above, each of R9 to R17 is selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, and a cyano group.
X represents an oxygen atom or a sulfur atom.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Each of
An organic compound according to the present embodiment is denoted by formula (1) below.
R1 to R8
In formula (1), each of R1 to R8 is selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, and a cyano group.
Examples of the halogen atom include fluorine, chlorine, bromine, and iodine, but the halogen atom is not limited to these.
Examples of the alkyl group include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a tert-butyl group, a sec-butyl group, an octyl group, a cyclohexyl group, a 1-adamantyl group, and 2-adamantyl group, but the alkyl group is not limited to these. The carbon number of the alkyl group can be 1 or more and 10 or less.
Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, a 2-ethyl-octyloxy group, and a benzyloxy group, but the alkoxy group is not limited to these. The carbon number of the alkoxy group can be 1 or more and 10 or less.
Examples of the amino group include an N-methylamino group, an N-ethylamino group, an N,N-dimethylamino group, an N,N-diethylamino group, an N-methyl-N-ethylamino group, an N-benzylamino group, an N-methyl-N-benzylamino group, an N,N-dibenzylamino group, an anilino group, an N,N-diphenylamino group, an N,N-dinaphthylamino group, an N,N-difluorenylamino group, an N-phenyl-N-tolylamino group, an N,N-ditolylamino group, an N-methyl-N-phenylamino group, an N,N-dianisolylamino group, an N-mesityl-N-phenylamino group, an N,N-dimesitylamino group, an N-phenyl-N-(4-tert-butylphenyl)amino group, an N-phenyl-N-(4-trifluoromethylphenyl)amino group, and an N-piperidyl group, but the amino group is not limited to these.
Examples of the aryloxy group or the heteroaryloxy group include a phenoxy group and a thienyloxy group, but the aryloxy group or the heteroaryloxy group is not limited to these.
Examples of the silyl group include a trimethylsilyl group and a triphenylsilyl group, but the silyl group is not limited to these.
Examples of the aromatic hydrocarbon group include a phenyl group, a naphthyl group, an indenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a phenanthryl group, a fluoranthenyl group, and triphenylenyl group, but the aromatic hydrocarbon group is not limited to these.
Examples of the heterocyclic group include a pyridyl group, an oxazolyl group, an oxadiazolyl group, a thiazolyl group, a thiadiazolyl group, a carbazolyl group, an acridinyl group, a phenanthrolyl group, a dibenzofuranyl group, and a dibenzothiophenyl group, but the heterocyclic group is not limited to these.
Examples of the substituent that may be further included in the above-described alkyl group, alkoxy group, amino group, aryloxy group, heteroaryloxy group, silyl group, aromatic hydrocarbon group, or heterocyclic group include a deuterium atom; halogen atoms such as fluorine, chlorine, bromine, and iodine; alkyl groups such as a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, and a tert-butyl group; alkoxy groups such as a methoxy group, an ethoxy group, and a propoxy group; amino groups, such as a dimethylamino group, a diethylamino group, a dibenzylamino group, a diphenylamino group, and a ditolylamino group; aryloxy groups such as a phenoxy group; aromatic hydrocarbon groups such as a phenyl group and a biphenyl group; heterocyclic groups such as a pyridyl group and a pyrrolyl group; and cyano groups, but the substituent is not limited to these.
In formula (1), A is a structure denoted by A below, * represents a position where bonding is performed.
In A above, B is selected from the group consisting of structures denoted by (B-1) to (B-15) below, * represents a position where bonding is performed. The two Bs may be the same or differ from each other but can be the same.
R9 to R17
In (B-1] to (B-15), each of R9 to R17 is selected from the group consisting of a hydrogen atom, a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted heteroaryloxy group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, and a cyano group.
Specific examples of the halogen atom, the alkyl group, the alkoxy group, the amino group, the aryloxy group, the heteroaryloxy group, the silyl group, the aromatic hydrocarbon group, or the heterocyclic group include the groups akin to that described with respect to R1 to R8, but the group is not limited to these. The carbon number of the alkyl group can be 1 or more and 10 or less. The carbon number of the alkoxy group can be 1 or more and 10 or less. In this regard, specific examples of the substituent that may be further included in the alkyl group, the alkoxy group, the amino group, the aryloxy group, the heteroaryloxy group, the silyl group, the aromatic hydrocarbon group, or the heterocyclic group include the substituents akin to that described with respect to R1 to R8, but the substituent is not limited to these.
X represents an oxygen atom or a sulfur atom.
B can be selected from the group consisting of structures denoted by (C-1) to (C-3) below.
B can be selected from the group consisting of structures denoted by (D-1) to (D-6) below.
Next, a method for synthesizing the organic compound according to the present embodiment will be described. The organic compound according to the present embodiment is synthesized in accordance with, for example, a reaction scheme described below.
Herein, various compounds are obtained by appropriately changing the compounds denoted by (b), (f), and the like above. The method for synthesizing the organic compound according to the present embodiment is not limited to the above-described synthesis scheme, and various synthesis schemes and reagents are usable. In this regard, the synthesis method will be described in detail in the examples.
Specific examples of the organic compound according to the present embodiment will be described below, but the organic compound is not limited to these, as a matter of course.
Exemplary compounds belonging to a group A are compounds in which B has a structure denoted by (B-1) to (B-6) and in which condensed rings B at both ends include a dibenzofuran ring, a dibenzothiophene ring, or a carbazole ring. These compounds are compounds in which, in particular, the carrier balance is readily adjusted since an oxygen atom, a sulfur atom, or a nitrogen atom is included in the condensed ring B, and the electric charge transportability is enhanced due to plentiful unshared electron pairs included in these atoms.
Exemplary compounds belonging to a group B are compounds in which B has a structure denoted by (B-7) to (B-11) and in which condensed rings B at both ends are composed of SP2 carbon. These compounds are compounds having, in particular, excellent stability since the condensed ring is composed of an SP2 hybrid orbital.
Exemplary compounds belonging to a group C are compounds in which B has a structure denoted by (B-12) to (B-15) and in which condensed rings B at both ends include a fluorene ring. These compounds including a methyl group at position 9 of the fluorene ring in a direction perpendicular to the in-plane direction of the fluorene ring enables condensed rings to be particularly suppressed from overlapping one another. Further, since including a tertiary alkyl group such as a t-Bu group as R9 to R15 enables intermolecular interaction to be suppressed from occurring, the compound has excellent sublimation properties regardless of a large molecular weight.
Next, the properties of the organic compound according to the present embodiment will be described. The organic compound according to the present embodiment has the following characteristics and, therefore, is a compound having high S1 (singlet energy) and T1 (triplet energy) and having excellent film performance and sublimation properties. Further, the compound being used enables an organic light-emitting element having excellent light emission efficiency and element durability to be provided.
(1) high S1 and T1 due to a 1,1′-biphenylene group that has a condensed ring B of three or more rings at position 3′ being bonded to positions 7 and 10 of dibenzo[f,h]quinoxaline
(2) high compound stability due to two 1,1′-biphenylene groups being included in the molecule, a hydrogen atom being included at a substitution position other than positions 3 and 3′ of the biphenylene group, and no substituent that increases a bonding distance being included
(1) S1 and T1 are high due to a 1,1′-biphenylene group that has a condensed ring B of three or more rings at position 3′ being bonded to positions 7 and 10 of dibenzo[f,h] quinoxaline.
Regarding the disclosure of the organic compound according to the present embodiment, the present inventors paid attention to the structure of a phenylene chain. Specifically, the organic compound according to the present embodiment has a structure in which a dibenzo[f,h]quinoxaline ring serves as a center and is bonded to each of two condensed rings B of three or more rings with a 1,1′-biphenylene group interposed therebetween. In the structure, since the dibenzo[f,h]quinoxaline ring and the condensed ring B of three or more rings are bonded to position 3 and position 3′, respectively, of the 1,1′-biphenylene group serving as a coupling group, S1 (singlet energy) and T1 (triplet energy) are increased.
In this regard, the results of comparisons of each of S1 (singlet energy) and T1 (triplet energy) between Exemplary compound A4 that is the organic compound according to the present embodiment and Comparative compound 1-C are presented in Table 1. Herein, S1 (singlet energy) and T1 (triplet energy) were determined based on molecular orbital calculation.
As presented in Table 1, S1 of Exemplary compound A4 is 3.58 eV, and T1 is 2.73 eV. On the other hand, S1 of Comparative compound 1-C is 3.28 eV, and T1 is 2.63 eV. Consequently, it is clear that Exemplary compound A4 exhibits higher values with respect to both S1 and T1.
The reason for this is conjectured to be that the coupling group includes a 1,1′-biphenylene structure and that the coupling group is bonded to position 7 and position 10 of the dibenzo[f,h]quinoxaline ring.
That is, when two 1,1′-biphenylene groups are bonded to position 6 and position 11, respectively, of the dibenzo[f,h]quinoxaline ring (positions-6,11-substituted product illustrated in
Herein, effects of the S1 energy and the T1 energy being high will be described. A phosphorescence light-emitting element is an organic light-emitting element which uses T1 energy for emitting light. A light-emitting layer host material of the organic light-emitting element can have higher T1 energy than the phosphorescence light-emitting material which emits phosphorescence. Regarding use as a carrier blocking layer around the light-emitting layer, S1 can be high in addition to high T1. In general, the S1 energy increases with increased T1 energy. On the other hand, high S1 energy corresponds to a large band gap. Consequently, regarding use as the light-emitting layer host material or the carrier blocking layer around the light-emitting layer, the stability is high under excessive concentration of excitons or unnecessary electric charge accumulation, and advantages can be provided in element durability. Therefore, the organic compound can have sufficiently high S1 energy and T1 energy.
The organic compound according to the present embodiment has sufficiently high S1 energy and T1 energy since the coupling group such as a 1,1′-biphenylene group is included at position 7 and position 10 of the dibenzo[f,h]quinoxaline ring and the condensed ring B is included at position 3′. Consequently, the organic compound being used as the light-emitting layer host material or the carrier blocking layer of the organic light-emitting element enables an element having a high efficiency and a long life to be provided.
In this regard, the calculation technique of the molecular orbital calculation method used a currently widespread density functional theory (DFT). Regarding a functional, B3LYP was used, and regarding a basis function, 6-31G* was used. In this regard, the molecular orbital calculation method was performed based on a currently widespread Gaussian09 (Gaussian09, RevisionC. 01, M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyed, E. Brothers, K. N. Kudin, V. N. Staroverov, T. Keith, R. Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene, J. E. Knox, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador, J. J. Danneberg, S. Dapprich, A. D. Daniels, O. Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian, Inc., Wallingford Conn., 2010.).
(2) The compound stability is high due to two 1,1′-biphenylene groups being included in the molecule, a hydrogen atom being included at a substitution position other than positions 3 and 3′ of the 1,1′-biphenylene group, and no substituent that increases a bonding distance being included.
Regarding the disclosure of the organic compound according to the present embodiment, the present inventors paid attention to the degree of freedom of rotation of a bond included in the organic compound. Specifically, the organic compound according to the present embodiment has a structure in which condensed rings of three or more rings, including a dibenzo[f,h]quinoxaline ring, are bonded to position 3 and position 3′ of two 1,1′-biphenylene group. Further, the organic compound according to the present embodiment has a structure in which a hydrogen atom is included at a substitution position other than positions 3 and 3′ of the 1,1′-biphenylene group, and no substituent that increases a bonding distance is included. Consequently, the organic compound has a high degree of freedom of rotation.
In this regard, the results of comparisons of the thermal properties between Exemplary compound A4 that is the organic compound according to the present embodiment and Comparative compound 1-A are presented in Table 2. Herein, Comparative compound 1-A is Compound 1-A described in US 2014/0034925.
As presented in Table 2, the molecular weight increases and, further, the degree of freedom of rotation of the bond increases due to biphenylene groups that bond the condensed rings B at both ends of the molecular structure.
In Comparative compound 1-A, carbazole rings are present as condensed rings at both ends, and a phenylene group serving as a coupling group is included between the carbazole ring and the dibenzoquinoxaline ring at the center. On the other hand, regarding the Exemplary compound A4, it is clear that the degree of freedom of rotation is larger than the Comparative compound 1-A since dibenzofuran rings are present as condensed rings B at both ends, and a biphenylene group serving as a coupling group is included between the dibenzofuran ring and the dibenzoquinoxaline ring at the center.
Since the molecular weight increases and, further, the degree of freedom of rotation of the bond increases due to biphenylene groups serving as a coupling group being introduced, the following effects are exerted.
First, the molecular weight being increased enables molecular packing in which molecules overlap one another to be suppressed from occurring, crystallization does not readily occur, and amorphousness is enhanced. In this regard, high amorphousness, that is, good film performance, is favorable in use for an organic light-emitting element. The reason for this is that crystal grain boundaries in accordance with fine crystallization, a trap level, and quencher generation do not readily occur during operation of the element due to high amorphousness, and that favorable carrier transportability and highly efficient light emission characteristics are maintained. As a result, an organic light-emitting element having excellent durability and efficiency is provided.
Herein, Table 2 presents the results of evaluation of the glass transition temperature and the crystallization temperature of Exemplary compound A4 and Comparative compound 1-A based on the differential scanning calorimetry (DSC) measurement. It can be said that glass transition temperature being higher and the crystallization temperature being high or not observed correspond to high amorphousness and excellent thermal stability. Regarding the DSC measurement, the glass transition temperature and the crystallization temperature were measured by sealing about 2 mg of sample in an aluminum pan, performing rapid cooling from a high temperature higher than the melting temperature so as to make the sample to take on an amorphous state, and increasing the temperature at a temperature increasing rate of 10° C./min. Regarding a measurement apparatus, DSC 204 F1 produced by NETZSCH was used.
Comparative compound 1-A had a glass transition temperature of 155° C., and the crystallization temperature was observed at 304° C. during increasing of the temperature. On the other hand, Exemplary compound A4 had a glass transition temperature of 133° C. and the crystallization temperature was not observed during increasing of the temperature. That is, there is no risk of a thin film formed by heat vapor deposition in a vacuum being crystallized, and it can be said that the compound has high amorphousness and more excellent thermal stability. Therefore, it is possible to provide an organic light-emitting element that is capable of maintaining a stable amorphous film during operation of the element and that has a long life.
Second, the degree of freedom of rotation being increased enables the sublimation temperature to be lowered so as to enhance the sublimation properties. When the degree of freedom of rotation is low, the sublimation properties are deteriorated since organic compounds readily aggregate with each other. Regarding Exemplary compound A4, since the molecular weight is simply increased compared with Comparative compound 1-A, the sublimation properties tend to be readily deteriorated. However, since the 1,1′-biphenylene groups are used as the coupling groups of three condensed rings present in the molecule so that the condensed rings are bonded at positions 3 and 3′ of the 1,1′-biphenylene groups, the degree of freedom of rotation is high so that intermolecular stacking is readily avoided. Therefore, a favorable film having no problem in sublimation properties is formed.
In this regard, the evaluation of the light emission characteristics and the thermal stability described in the features (1) and (2) of the organic compound according to the present embodiment will be described in the examples later in more detail.
In addition, when the organic compound according to the present embodiment further has the following features, the organic compound is particularly suitable for an organic light-emitting element.
(3) condensed rings B at both ends including no SP3 carbon
(4) condensed rings B at both ends being bonded to coupling groups at substitution positions without interference due to steric hindrance
These features will be described below.
(3) The condensed rings B at both ends include no SP3 carbon.
Regarding the organic compound according to the present embodiment, the dibenzoquinoxaline ring and the biphenylene group serving as the coupling group can include no SP3 carbon, and, in addition, the condensed rings B at both ends can include no SP3 carbon. The reason for this is that since a carbon-carbon bond of SP2 carbon has a large bonding energy, cleavage of the bond is not readily occur during operation of the organic light-emitting element. Consequently, from the viewpoint of an improvement of element durability, the condensed rings B at both ends can have no SP3 carbon. Specifically, B can have a structure denoted by (B-1) to (B-11), and the condensed ring B can be a phenanthrene ring, a dibenzofuran ring, a dibenzothiophene ring, or a carbazole ring.
(4) The condensed rings B at both ends are bonded to coupling groups at substitution positions without interference due to steric hindrance.
In the organic compound according to the present embodiment, the condensed rings B at both ends can be bonded to the coupling groups at substitution positions without interference due to steric hindrance. The reason for this is that when interfere between the condensed ring B and the coupling group due to steric hindrance does not occur, since the bonding distance between the condensed ring B and the coupling group is not readily increased, the bond is not readily cleaved.
Herein, the result of a comparison of the bonding distance between Exemplary compound B2 and Exemplary compound B3 is presented in Table 3.
In Table 3, the bond between the condensed ring B and the coupling group is denoted as a, and the dihedral angle thereof is presented. The dihedral angle of Exemplary compound B2 is 36.5°, whereas the dihedral angle of Exemplary compound B3 is 57.0°. This means that Exemplary compound B2 has higher planarity under the influence of steric hindrance of a hydrogen atom at peri-position of the phenanthrene ring. A carrier mobility increases with increasing planarity. Regarding a structure having high planarity such as Exemplary compound B2, the heat resistance is improved and a bond is not readily cleaved.
Therefore, the condensed ring B can be bonded to the coupling group at a substitution position without interference due to steric hindrance.
In this regard, the bonding distance was visualized using the molecular orbital calculation.
The organic light-emitting element according to the present embodiment includes at least a pair of electrodes composed of an anode and a cathode and an organic compound layer disposed between the electrodes. In the organic light-emitting element according to the present embodiment, the organic compound layer may be a single layer or a stacked body composed of a plurality of layers provided that a light-emitting layer is included. Herein, when the organic compound layer is a stacked body composed of a plurality of layers, the organic compound layer may include, in addition to a light-emitting layer, a hole injection layer, a hole transport layer, an electron blocking layer, a hole exciton blocking layer, an electron transport layer, an electron injection layer, and the like. In this regard, the light-emitting layer may be a single layer or a stacked body composed of a plurality of layers.
In the organic light-emitting element according to the present embodiment, the organic compound according to the present embodiment is contained in at least one layer of the organic compound layer. Specifically, the organic compound according to the present embodiment is contained in any one of the light-emitting layer, the hole injection layer, the hole transport layer, the electron blocking layer, the light-emitting layer, the hole exciton blocking layer, the electron transport layer, the electron injection layer, and the like. The organic compound according to the present embodiment can be contained in the light-emitting layer.
In the organic light-emitting element according to the present embodiment, when the organic compound according to the present embodiment is contained in the light-emitting layer, the light-emitting layer may be a layer composed of only the organic compound according to the present embodiment or a layer composed of the organic compound according to the present embodiment and other compounds. Herein, when the light-emitting layer is composed of the organic compound according to the present embodiment and other compounds, the organic compound according to the present embodiment may be used as a host of the light-emitting layer or may be used as a guest. Alternatively, the organic compound may be used as an assist material that may be contained in the light-emitting layer. In this regard, the host is a compound having the largest mass ratio in the compounds constituting the light-emitting layer. The guest is a compound that has a smaller mass ratio than the host in the compounds constituting the light-emitting layer and that has a responsibility for main light emission. The assist material is a compound that has a smaller mass ratio than the host in the compounds constituting the light-emitting layer and that assists the guest in emitting light. In this regard, the assist material is also called a second host.
The present inventors performed various research and found that the organic compound according to the present embodiment being used as the host or the assist of the light-emitting layer, in particular, as the host, enables an element which produces high-efficiency and high-luminance optical output and which has very high durability to be obtained. The light-emitting layer may be a single layer or a multilayer and, for example, color mixing may be performed by setting the emission color of the present embodiment to be green color emission and containing a light-emitting material having another emission color. The multilayer means a state in which the light-emitting layer and another light-emitting layer are stacked. In such an instance, the emission color of the organic light-emitting element is not limited to green. More specifically, the emission color may be a white color or may be an intermediate color. When the color is white, other light-emitting layers emit colors other than green, that is, blue and red. Regarding a film formation method, the film is formed by vapor deposition or coating film formation. The detail will be described later in the example.
The organic compound according to the present embodiment may be used as a constituent material of organic compound layers other than the light-emitting layer constituting the organic light-emitting element according to the present embodiment. Specifically, the organic compound may be used as a constituent material of the electron transport layer, the electron injection layer, the hole transport layer, the hole injection layer, the hole blocking layer, and the like. In such an instance, the emission color of the organic light-emitting element is not limited to green. More specifically, the emission color may be a white color or may be an intermediate color.
The compound according to the present embodiment can be used in the light-emitting layer in the organic light-emitting element under the following conditions.
(1) content of the compound according to the present embodiment used in the light-emitting layer being 30% by mass or more and 99% by mass or less
(2) a light-emitting material mixed with the compound according to the present embodiment in the light-emitting layer being a phosphorescence light-emitting material, and the phosphorescence light-emitting material being an organometallic complex including a condensed ring of three or more rings as a ligand
The above-described conditions will be described below.
(1) The content of the compound according to the present embodiment used in the light-emitting layer is 30% by mass or more and 99% by mass or less.
When the organic compound according to the present embodiment is used for the light-emitting layer, the content can be 30% by mass or more and 99% by mass or less relative to a total light-emitting layer. The organic compound according to the present embodiment has high amorphousness and, therefore, is a material suitable for the host material of the light-emitting layer. When the organic compound is used as the host material, the content is preferably 50% by mass or more and 99% by mass or less and more preferably 70% by mass or more and 99% by mass or less. The compound is a hard-to-crystallize material even when used at a content of 99% by mass and, therefore, realizes a function with excellent characteristics. From the viewpoint of an improvement in the film performance of the light-emitting layer, the organic compound may be used as the assist material. When the organic compound is used as the assist material, the content may be 30% by mass or more and less than 50% by mass. This is caused by the structural feature of the organic compound according to the present embodiment. Since the compound is not readily aggregated so that crystal boundaries due to aggregation of molecules do not readily occur even under operation of the organic light-emitting element, a light-emitting element having excellent characteristics is provided.
(2) A light-emitting material mixed with the compound according to the present embodiment in the light-emitting layer is a phosphorescence light-emitting material, and the phosphorescence light-emitting material is an organometallic complex including a condensed ring of three or more rings as a ligand.
The organic compound according to the present embodiment is a compound including a condensed ring B of three or more rings at both ends. Consequently, the phosphorescence light-emitting material used with the organic compound according to the present embodiment in the light-emitting layer can have a structure in which π conjugation of the ligand is extended. More specifically, an organometallic complex including a condensed ring of three or more rings in a structure of the ligand can be adopted. The reason for this is that, in a manner similar to the organic compound according to the present embodiment that serves as the host material, the organometallic complex that serves as the guest material having a high-planarity structure enables high-planarity sections to approach one another due to an interaction. More specifically, a planar portion of the host material and a ligand of the organometallic complex readily approach one another. Consequently, it is expected that the intermolecular distance between the host material and the organometallic complex be reduced.
Herein, regarding the triplet energy used for the phosphorescence light-emitting material, it is known that energy is transferred due to Dexter electron transfer. In the Dexter electron transfer, energy is transferred by contact of molecules with each other. That is, the intermolecular distance between the host material and the guest material being reduced makes energy transfer from the host material to the guest material to be performed efficiently. The high-planarity organometallic complex that includes a condensed ring of three or more rings in the structure of the ligand being used reduces the intermolecular distance between the host material that is an organic compound according to the present embodiment and the organometallic complex so that energy transfer from the host to the organometallic complex readily occurs. As a result, a high-efficiency organic light-emitting element is provided.
In this regard, the high-planarity condensed ring structure of three or more rings included in the ligand denotes, for example, a triphenylene ring, a phenanthrene ring, a fluorene ring, a benzofluorene ring, a dibenzofuran ring, a dibenzothiophene ring, a benzoisoquinoline ring, and a naphthoisoquinoline ring. That is, the organometallic complex in which at least any one of these structures is included in the ligand being used for the light-emitting material enables the organic compound according to the present embodiment to provide a higher-efficiency light-emitting element.
Specific examples of the organometallic complex are described below, but the organometallic complex is not limited to these, as a matter of course. Specific examples of the organometallic complex include organometallic complexes having a partial structure denoted by formulae [Ir-1] to [Ir-16] below.
In formulae [Ir-1] to [Ir-16], each of Ar1 and Ar2 is selected from the group consisting of a deuterium atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted silyl group, a substituted or unsubstituted aromatic hydrocarbon group, a substituted or unsubstituted heterocyclic group, and a cyano group, p represents an integer of 0 or more and 4 or less, when p is 2 or more, a plurality of Ar1s may be the same or differ from each other, q represents an integer of 0 or more and 4 or less, and when q is 2 or more, a plurality of Ar2s may be the same or differ from each other.
X is selected from the group consisting of an oxygen atom, a sulfur atom, a substituted or unsubstituted carbon atom, and a substituted or unsubstituted nitrogen atom. Examples of the substituent of the carbon atom or the nitrogen atom include a substituted or unsubstituted alkyl group and a substituted or unsubstituted aromatic hydrocarbon group.
m represents an integer of 1 or more and 3 or less, and when m is 2 or more, a plurality of ligands may be the same or differ from each other.
A condensed ring bonded to a pyridine ring in formulae [Ir-1] to [Ir-8] and a condensed ring bonded to a benzene ring in formulae [Ir-9] to [Ir-16] may have a substituent such as a deuterium atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, and a cyano group.
Examples of the halogen atom, the alkyl group, the alkoxy group, the silyl group, the aromatic hydrocarbon group, and the heterocyclic group in formulae [Ir-1] to [Ir-16] include the materials akin to that described with respect to R1 to R8, but the above are not limited to these materials. The carbon number of the alkyl group is preferably 1 or more and 10 or less. In this regard, specific examples of the substituent that may be further included in the alkyl group, the silyl group, the aromatic hydrocarbon group, or the heterocyclic group include the materials akin to that described with respect to R1 to R8, but the substituent is not limited to these materials.
Of the organometallic complexes having a partial structure denoted by formulae [Ir-1] to [Ir-16] above, organometallic complexes including a condensed ring of three or more rings in the ligand are further favorable. Specifically, the favorable organometallic complex has a partial structure denoted by formulae [Ir-3] to [Ir-8] or [Ir-11] to [Ir-16] above. Specific examples of the organometallic complex are described below, but the organometallic complex is not limited to these, as a matter of course.
Exemplary compounds belonging to an AA group or a BB group are metal complexes having a partial structure denoted by formula [Ir-3] and are compounds including at least a phenanthrene ring in the ligand. These compounds are compounds having, in particular, excellent stability since the condensed ring is composed of an SP2 hybrid orbital.
Exemplary compounds belonging to a CC group are metal complexes having a partial structure denoted by formula [Ir-4] and are compounds including at least a triphenylene ring in the ligand. These compounds are compounds having, in particular, excellent stability since the condensed ring is composed of an SP′ hybrid orbital.
Exemplary compounds belonging to a DD group are metal complexes having a partial structure denoted by formulae [Ir-5] to [Ir-8] and are compounds including at least a dibenzofuran ring, a dibenzothiophene ring, a benzonaphthofuran ring, or a benzonaphthothiophene ring in the ligand. These compounds are compounds which are, in particular, easy-to-adjust a carrier balance since the condensed ring includes an oxygen atom or a sulfur atom so that the electric charge transportability is enhanced due to plentiful unshared electron pairs included in these atoms.
Exemplary compounds belonging to an EE group to a GG group are metal complexes having a partial structure denoted by formulae [Ir-6] to [Ir-8] and are compounds including at least a benzofluorene ring in the ligand. These compounds including a substituent at position 9 of the fluorene ring in a direction perpendicular to the in-plane direction of the fluorene ring enables condensed rings to be particularly suppressed from overlapping one another. Consequently, these compounds have, in particular, excellent sublimation properties.
Exemplary compounds belonging to an HH group are metal complexes having a partial structure denoted by formulae [Ir-11] to [Ir-13] and are compounds including at least a benzoisoquinoline ring in the ligand. These compounds are compounds which are, in particular, easy-to-adjust a carrier balance since the condensed ring includes a nitrogen atom so that the electric charge transportability is enhanced due to an unshared electron pair included in the atom and high electronegativity.
Exemplary compounds belonging to an II group are metal complexes having a partial structure denoted by formula [Ir-14] and are compounds including at least a naphthoisoquinoline ring in the ligand. These compounds are compounds which are, in particular, easy-to-adjust a carrier balance since the condensed ring includes a nitrogen atom so that the electric charge transportability is enhanced due to an unshared electron pair included in the atom and high electronegativity.
Compounds Other than Organic Compound According to Present Embodiment
As the situation demands, a known low-molecular-weight-based or polymer-based hole injection compound or hole transport compound, compound serving as the host, light-emitting compound, electron injection compound, electron transport compound, or the like may be used in combination in addition to the organic compound according to the present embodiment. Examples of these compounds will be described below.
The hole transport compound is favorably a material having high hole mobility to facilitate injection of a hole from an anode and to enable the injected hole to be transported to the light-emitting layer. In addition, a material having a high glass transition temperature is favorable to suppress the film quality such as crystallization from deteriorating in the organic light-emitting element. Examples of the low-molecular-weight-based or polymer-based material having hole injection-transport performance include triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, stilbene derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole)s, poly(thiophen)s, and other conductive polymers. Further, the above-described hole injection-transport materials are also favorably used for the electron blocking layer. Specific examples of the compound used as the hole injection-transport material will be described below, but the compound is not limited to these, as a matter of course.
Examples of the light-emitting material mainly involved in the light-emitting function include condensed ring compounds (for example, fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, and rubrene), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organic aluminum complexes such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives. Specific examples of the compound used as the light-emitting material will be described below, but the compound is not limited to these, as a matter of course.
A compound other than the organic compound according to the present embodiment may be contained as a third component serving as the light-emitting layer host or the light-emission assist material included in the light-emitting layer. Examples of the third component include aromatic hydrocarbon compounds or derivatives thereof, carbazole derivatives, azine derivatives, xanthone derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organic aluminum complexes such as tris(8-quinolinolato)aluminum, and organic beryllium complexes.
In particular, the assist material can be a material having a carbazole skeleton, a material including an azine ring such as a diazine ring or a triazine ring in the skeleton, and a material including xanthone in the skeleton. The reason for this is that these materials are easy-to-adjust the HOMO level and the LUMO level due to a high electron donating property or a high electron attracting property. Since the organic compound according to the present embodiment has a structure in which the condensed rings B of three or more rings are bonded to both ends of a biphenylene chain, the band gap is increased to some extent. Therefore, a material having the above-described skeleton capable of adjusting the HOMO level and the LUMO level is particularly favorable as the assist material. When these assist materials and the organic compound according to the present embodiment are combined, a favorable carrier balance is realized.
Specific examples of the compound used as the light-emitting layer host or the light-emission assist material included in the light-emitting layer will be described below, but the compound is not limited to these, as a matter of course. Of the specific examples below, the materials which have a carbazole skeleton and which are favorable as the assist material are EM32 to EM38. The materials which include an azine ring in the skeleton and which are favorable as the assist material are EM35, EM36, EM37, EM38, EM39, and EM40. The materials which include xanthone in the skeleton and which are favorable as the assist material are EM28 and EM30.
The electron transport material may be arbitrarily selected from materials capable of transporting an electron injected from the cathode to the light-emitting layer and is selected in consideration of, for example, a balance with the hole mobility of the hole transport material. Examples of the material having an electron transporting capability include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organic aluminum complexes, and condensed ring compounds (for example, fluorene derivatives, naphthalene derivatives, chrysene derivatives, and anthracene derivatives). Further, the above-described electron transport material is favorably used for the hole blocking layer. Specific examples of the compound used as the electron transport material will be described below, but the compound is not limited to these, as a matter of course.
The organic light-emitting element is disposed by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, a microlens, and the like may be disposed on the second electrode. When the color filter is disposed, a planarization layer may be disposed between the protective layer and the color filter. The planarization layer may be composed of an acrylic resin or the like. The same applies when the planarization layer is disposed between the color filter and the microlens.
Examples of the substrate include quartz, glass, silicon wafers, resins, and metals. A wiring line and a switching element such as a transistor are provided on the substrate, and an insulating layer may be provided thereon. There is no particular limitation regarding the material for forming the insulating layer provided that it is possible to form a contact hole for forming a wiring line connected to the first electrode and to ensure insulation from a wiring line which is not connected. For example, a resin such as a polyimide, silicon oxide, or silicon nitride may be used.
A pair of electrodes may be used as the electrodes. The pair of electrodes may be an anode and a cathode.
When an electric field is applied in the direction of light emission from the organic light-emitting element, an electrode at a higher potential is the anode, and the other is the cathode. It can also be said that an electrode which supplies a hole to the light-emitting layer is the anode, and an electrode which supplies an electron is the cathode.
The material constituting the anode can have as large a work function as possible. For example, simple metals, such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten, mixtures containing these, alloys of combination of these, and metal oxides, such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide are usable. In addition, conductive polymers, such as polyanilines, polypyrroles, and polythiophenes, are also usable.
One type of these electrode substances may be used alone, or at least two types may be used in combination. In this regard, the anode may be composed of a single layer or a plurality of layers.
For example, chromium, aluminum, silver, titanium, tungsten, or molybdenum or an alloy or a stacked body of these may be used as a reflection electrode. The above-described materials are capable of functioning as a reflection film having no role as an electrode. For example, an oxide transparent conductive layer of indium tin oxide (ITO), indium zinc oxide, or the like may be used as a transparent electrode, but the material is not limited to these.
A photolithography technology may be used for forming the electrode.
On the other hand, favorably, the material constituting the cathode has a small work function. Examples include simple metals, such as lithium or other alkali metals, calcium or other alkaline-earth metals, aluminum, titanium, manganese, silver, lead, and chromium, and mixtures containing these. Alternatively, alloys of combinations of these simple metals may also be used. For example, magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver may be used. Metal oxides such as indium tin oxide (ITO) may also be used. One type of these electrode materials may be used alone, or at least two types may be used in combination. The cathode may have a single layer configuration or a multilayer configuration. Of these, silver is favorably used, and a silver alloy is more favorable so as to reduce aggregation of silver. There is no particular limitation regarding the ratio of the alloy provided that aggregation of silver is reduced. For example, silver:other metal may be 1:1, 3:1, or the like.
There is no particular limitation regarding the cathode, and the cathode may be a top emission element by using an oxide conductive layer such as ITO or a bottom emission element by using a reflection electrode such as aluminum (Al). There is no particular limitation regarding the method for forming the cathode, and, more favorably, a direct current sputtering method, an alternating current sputtering method, or the like is used since coverage of the film is favorable so that the resistance of the film is readily reduced.
The organic compound layer may be formed from a single layer or a plurality of layers. When a plurality of layers are included, the layers may be referred to as a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, or an electron injection layer in accordance with the function of the layer. The organic compound layer is mainly composed of an organic compound but may contain an inorganic atom and an inorganic compound. For example, copper, lithium, magnesium, aluminum, iridium, platinum, molybdenum, or zinc may be contained. The organic compound layer may be disposed between a first electrode and a second electrode or be disposed in contact with the first electrode and the second electrode.
The organic compound layer (a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and the like) constituting the organic light-emitting element according to an embodiment of the present disclosure is formed by a method described below.
Regarding the organic compound layer constituting the organic light-emitting element according to an embodiment of the present disclosure, a dry process, such as a vacuum vapor deposition method, an ionization vapor deposition method, sputtering, or plasma, may be used. In place of the dry process, a wet process in which dissolution into an appropriate solvent is performed, and a layer is formed by a known coating method (for example, spin coating, dipping, a casting method, an LB method, or an ink jet method) may be used.
In this regard, when a layer is formed by a vacuum vapor deposition method, a solution coating method, or the like, crystallization and the like does not readily occur, and the stability over time is excellent. In addition, when a film is formed by a coating method, a film may be formed in combination with an appropriate binder resin.
Examples of the binder resin include polyvinylcarbazole resins, polycarbonate resins, polyester resins, ABS resins, acrylic resins, polyimide resins, phenol resins, epoxy resins, silicon resins, and urea resins, but the binder resin is not limited to these.
One type of the binder resins may be used alone as a homopolymer or a copolymer, or at least two types may be used in combination. Further, as the situation demands, known plasticizers, antioxidants, ultraviolet absorbents, and the like may be used in combination.
The protective layer may be disposed on the second electrode. For example, glass provided with a moisture absorbent being bonded to the second electrode enables water and the like to be suppressed from entering the organic compound layer and enables defective display to be suppressed from occurring. In another embodiment, a passivation film of silicon nitride or the like may be disposed on the second electrode so as to suppress water and the like from entering the organic compound layer. For example, the second electrode may be formed and, thereafter, transported to another chamber without breaking a vacuum, and a silicon nitride film having a thickness of 2 μm may be formed by a CVD method so as to serve as the protective layer. After film formation by the CVD method, a protective layer may be formed by using an atomic layer deposition (ALD) method. There is no particular limitation regarding the material for forming the film by the ALD method, and the material may be silicon nitride, silicon oxide, aluminum oxide, or the like. Further, a silicon nitride film may be formed by a CVD method on the film formed by the ALD method. The film formed by the ALD method may have smaller film thickness than the film formed by the CVD method. Specifically, the film thickness may be 50% or less and, further, 10% or less.
A color filter may be disposed on the protective layer. For example, a color filter in consideration of the size of the organic light-emitting element may be disposed on another substrate, and the resulting substrate may be bonded to the substrate provided with the organic light-emitting element, or a color filter may be patterned on the protective layer by using a photolithography technology. The color filter may be composed of a polymer.
The planarization layer may be included between the color filter and the protective layer. The planarization layer is disposed to reduce unevenness of an underlying layer. The layer may also called a resin material layer without limiting the purpose. The planarization layer may be composed of an organic compound and may be a low-molecular-weight compound or a polymer. The planarization layer can be a polymer.
The planarization layer may be disposed on and under the color filter, and the constituent materials thereof may be the same or may differ from each other. Specific examples include polyvinylcarbazole resins, polycarbonate resins, polyester resins, ABS resins, acrylic resins, polyimide resins, phenol resins, epoxy resins, silicon resins, and urea resins.
The organic light-emitting element or the organic light emitting apparatus may include an optical member such as a microlens on the light-emitting side thereof. The microlens may be composed of an acrylic resin, an epoxy resin, or the like. The microlens may have purposes of increasing the amount of light extracted from the organic light-emitting element or the organic light-emitting apparatus and controlling the direction of the extracted light. The microlens may have a hemispherical shape. In the instance of a hemispherical shape, among tangents in contact with the hemisphere, there is a tangent parallel to the insulating layer, and the contact point between the tangent and the hemisphere is the vertex of the microlens. The vertex of the microlens is determined in the same manner in any sectional view. That is, among the tangents in contact with the semicircle of the microlens in the sectional view, there is a tangent parallel to the insulating layer, and the contact point between the tangent and the semicircle is the vertex of the microlens.
The midpoint of the microlens may also be defined. In a section of the microlens, a line segment from a point where an arc shape ends to another point where the arch shape ends is assumed, and the midpoint of the line segment may be referred to as the midpoint of the microlens. The section in which the vertex and the midpoint are determined may be a section perpendicular to the insulating layer.
An opposite substrate may be disposed on the planarization layer. The opposite substrate is disposed at a position corresponding to the above-described substrate and thus is referred to as an opposite substrate. The opposite substrate may be composed of the same material as the above-described substrate. When the above-described substrate is defined as a first substrate, the opposite substrate may be defined as a second substrate.
A light-emitting apparatus including the organic light-emitting element may include a pixel circuit connected to the organic light-emitting element. The pixel circuit may be an active matrix-type circuit that independently controls light emission of a first light-emitting element and a second light-emitting element. The active matrix-type circuit may be a voltage programming or current programming circuit. A driving circuit has a pixel circuit for each pixel. The pixel circuit may have a light-emitting element, a transistor that controls the emission luminance of the light-emitting element, a transistor that controls the timing of light emission, a capacitor that holds the gate voltage of the transistor for controlling the emission luminance, and a transistor for connecting to GND without through the light-emitting element.
The light-emitting apparatus has a display region and a peripheral region disposed around the display region. The display region includes a pixel circuit, and the peripheral region includes a display control circuit. The mobility of transistors constituting the pixel circuit may be smaller than the mobility of transistors constituting the display control circuit.
The slope of the current-voltage characteristics of the transistors constituting the pixel circuit may be smaller than the slope of the current-voltage characteristics of the transistors constituting the display control circuit. The slope of the current-voltage characteristics can be measured based on the so-called Vg-Ig characteristics. The transistors constituting the pixel circuit are transistors connected to light-emitting elements such as a first light-emitting element.
The organic light-emitting apparatus including the organic light-emitting element may include a plurality of pixels. The pixel includes subpixels each emitting light of a color that differ from colors of other subpixels. For example, the subpixels may have emission colors of RGB, respectively.
The pixel emits light from a region that is also called a pixel aperture. This region is the same as a first region. The pixel aperture may have a size of 15 μm or less and 5 μm or more. More specifically, the pixel aperture may be, for example, 11 μm, 9.5 μm, 7.4 μm, or 6.4 μm. The distance between the subpixels may be 10 μm or less and may be specifically 8 μm, 7.4 μm, or 6.4 μm.
The pixels may have a publicly known arrangement form in plan view. For example, the arrangement form may be the stripe arrangement, the delta arrangement, the PenTile arrangement, or the Bayer arrangement. The subpixels may have any publicly known shape in plan view. For example, the shape may be a hexagon or a quadrangle such as a rectangle or a rhombus. Of course, figures that are not exactly rectangles but are close to rectangles are also regarded as rectangles. The shape of the subpixels and the pixel arrangement may be used in combination.
The organic light-emitting element according to the present embodiment may be used as a constituent member of a display apparatus or an illumination apparatus. In addition, the organic light-emitting element is used in, for example, an exposure light source of an electrophotographic image forming apparatus, a backlight of a liquid crystal display apparatus, and a light-emitting apparatus including a color filter as a white light source.
The display apparatus may be an image information processing apparatus that includes an image input unit to which image information is input from an area CCD, a linear CCD, a memory card, or the like and an information processing unit configured to process the input information and that displays an input image on a display unit. The display apparatus may have a plurality of pixels, and at least one of the plurality of pixels may include the organic light-emitting element according to the present embodiment and a transistor connected to the organic light-emitting element.
The display unit included in an imaging apparatus or an ink jet printer may have a touch panel function. There is no particular limitation regarding the driving system of the touch panel function, and the system may be an infrared system, an electrostatic capacitance system, a resistive film system, or an electromagnetic induction system. The display apparatus may be used in a display unit of a multifunctional printer.
Next, a display apparatus according to the present embodiment will be described with reference to the drawings.
A transistor and a capacitative element may be disposed in a layer under or in the interior of the interlayer insulating layer 1.
The transistor may be electrically connected to the first electrode 2 through a contact hole or the like not illustrated in the drawing.
The insulating layer 3 is also referred to as a bank or a pixel isolation film. The insulating layer 3 is disposed covering the end of the first electrode 2 and surrounding the first electrode 2. A portion not provided with the insulating layer 3 is in contact with the organic compound layer 4 and serves as a light-emitting region.
The organic compound layer 4 includes a hole injection layer 41, a hole transport layer 42, a first light-emitting layer 43, a second light-emitting layer 44, and an electron transport layer 45.
The second electrode 5 may be a transparent electrode, a reflection electrode, or a semitransparent electrode.
The protective layer 6 reduces permeation of moisture into the organic compound layer 4. The protective layer 6 is a single layer in the drawing but may be a plurality of layers. An inorganic compound layer and an organic compound layer may be included on a layer basis.
The color filter 7 is divided into 7R, 7G, and 7B in accordance with the respective color. The color filter 7 may be formed on the planarization layer not illustrated in the drawing. A resin protective layer may be included on the color filter 7. Alternatively, the color filter 7 may be formed on the protective layer 6. Alternatively, the color filter 7 may be formed on the opposite substrate such as a glass substrate and, thereafter, may be bonded.
A display apparatus 100 illustrated in
An electrical connection system between the electrodes (anode 21 and cathode 23) included in the organic light-emitting element 26 and the electrodes (source electrode 17 and drain electrode 16) included in the TFT 18 is not limited to the form illustrated in
Regarding the display apparatus 100 illustrated in
In the display apparatus 100 illustrated in
The transistor used in the display apparatus 100 illustrated in
The transistor included in the display apparatus 100 illustrated in
The emission luminance of the organic light-emitting element according to the present embodiment is controlled by the TFT that is an example of the switching element, and a plurality of organic light-emitting elements being disposed in a plane enables an image to be displayed with the respective emission luminance. In this regard, the switching element according to the present embodiment is not limited to the TFT and may be a transistor formed of a low-temperature polysilicon or an active matrix driver formed on a substrate such as a Si substrate. “On the substrate” may translate into “in the substrate”. Whether the transistor is disposed in the substrate or the TFT is used is selected in accordance with the size of the display unit. For example, when the size is about 0.5 inches, it is favorable that the organic light-emitting element be disposed on the Si substrate.
The display apparatus according to the present embodiment may include a color filter having red, green, and blue colors. The red, green, and blue colors of the color filter may be arranged in the delta arrangement.
The display apparatus according to the present embodiment may be used in a display unit of a portable terminal. In such an instance, the display apparatus may have both a display function and an operation function. Examples of the portable terminal include mobile phones such as smart phones, tablets, and head mount displays.
The display apparatus according to the present embodiment may be used in a display unit of an imaging apparatus including an optical unit that includes a plurality of lenses and an imaging element that receives light passed through the optical unit. The imaging apparatus may include a display unit that displays information acquired by the imaging element. The display unit may be a display unit exposed to the outside of the imaging apparatus or a display unit disposed in a viewfinder. The imaging apparatus may be a digital camera or a digital camcorder.
Since the suitable timing for imaging is a very short period of time, it is desirable to display information as quickly as possible. Accordingly, a display apparatus that includes the organic light-emitting element according to the present embodiment can be used. This is because the organic light-emitting element has a high response speed. The display apparatus that includes an organic light-emitting element is more suitable than liquid crystal display apparatuses for use in these apparatuses for which a high display speed is required.
The imaging apparatus 1100 includes an optical unit not illustrated in the drawing. The optical unit includes a plurality of lenses and forms an image on an imaging element contained in the housing 1104. The plurality of lenses may adjust the focal point by adjusting their relative positions. This operation may be automatically performed. The imaging apparatus may also be referred to as a photoelectric conversion apparatus. The photoelectric conversion apparatus may employ, instead of a method in which images are successively imaged, imaging methods such as a method in which a difference from the previous image is detected and a method in which images are extracted from continuously recorded images.
The illumination apparatus is, for example, an apparatus that illuminates a room. The illumination apparatus may emit light of a color such as white, natural white, or any other color from blue to red. The illumination apparatus may include a light modulating circuit configured to modulate the light.
The illumination apparatus may include the organic light-emitting element according to the present disclosure and a power supply circuit connected to the organic light-emitting element. The power supply circuit is a circuit configured to convert alternating current voltage to direct current voltage. The white is a color having a color temperature of 4,200 K, and the natural white is a color having a color temperature of 5,000 K. The illumination apparatus may include a color filter.
The illumination apparatus according to the present embodiment may include a heat dissipation unit. The heat dissipation unit dissipates heat in the apparatus to the outside of the apparatus. The heat dissipation unit may be formed of, for example, a metal having a high specific heat or liquid silicon.
The tail lamp 1501 may include the organic light-emitting element according to the present embodiment. The tail lamp may include a protective member that protects the organic light-emitting element. There is no particular limitation regarding the material for forming the protective member provided that the material has high strength to a certain extent and is transparent, and the protective member can be composed of a polycarbonate or the like. The polycarbonate may be mixed with a furandicarboxylic acid derivative, an acrylonitrile derivative, or the like.
The automobile 1500 may include a car body 1503 and a window 1502 installed to the car body 1503. The window 1502 may be a transparent display unless it is a window for checking the front and the rear of the automobile. The transparent display may include the organic light-emitting element according to the present embodiment.
In such an instance, the constituent materials, such as the electrodes, included in the organic light-emitting element are formed of transparent members.
The moving object according to the present embodiment may be, for example, a ship, an aircraft, or a drone. The moving object may include a bodywork and a lighting fixture installed to the bodywork. The lighting fixture may emit light to indicate the position of the bodywork. The lighting fixture includes the organic light-emitting element according to the present embodiment.
Examples of applications of the display apparatuses according to the embodiments above will be described with reference to
The glasses 1600 further include a control unit 1603. The control unit 1603 functions as a power supply that supplies electric power to the imaging apparatus 1602 and the display apparatus. The control unit 1603 controls the operation of the imaging apparatus 1602 and the display apparatus. An optical system for focusing light on the imaging apparatus 1602 is formed on the lens 1601.
The control unit 1612 may have a gaze detection unit that detects the gaze of the wearer. Infrared rays may be used to detect the gaze. An infrared light-emitting unit emits infrared light to an eyeball of the user who is gazing at a displayed image. The emitted infrared light is reflected by the eyeball, and the reflected light is detected by an imaging unit including a light-receiving element so as to provide an imaged image of the eyeball. The deterioration of the image quality is reduced by providing a reducing unit that reduces light from the infrared light-emitting unit to a display unit in plan view. The gaze of the user to the displayed image is detected from the imaged image of the eyeball imaged with the infrared light. Any publicly known method is applicable to the gaze detection using the imaged image of the eyeball. As an example, a gaze detection method based on the Purkinje image formed by the reflection of irradiation light on the cornea is employed. More specifically, a gaze detection process based on a pupil-corneal reflection method is performed. The pupil-corneal reflection method is used, on the basis of the image of the pupil and the Purkinje image included in the imaged image of the eyeball, to calculate a gaze vector representing the direction (rotation angle) of the eyeball, thereby detecting the gaze of the user.
A display apparatus according to an embodiment of the present disclosure may include an imaging apparatus having a light-receiving element and may control a displayed image of the display apparatus on the basis of the gaze information of the user from the imaging apparatus. Specifically, in the display apparatus, a first field-of-view region at which the user gazes and a second field-of-view region other than the first field-of-view region are determined on the basis of the gaze information. The first field-of-view region and the second field-of-view region may be determined by the control unit of the display apparatus or may be determined by receiving those determined by an external control unit. In the display region of the display apparatus, the display resolution of the first field-of-view region may be controlled to be higher than the display resolution of the second field-of-view region. That is, the resolution of the second field-of-view region may be controlled to be lower than that of the first field-of-view region.
The display region includes a first display region and a second display region different from the first display region. A region of higher priority is determined from the first display region and the second display region on the basis of the gaze information. The first display region and the second display region may be determined by the control unit of the display apparatus or may be determined by receiving those determined by an external control unit. The resolution of a region of higher priority may be controlled to be higher than the resolution of a region other than the region of higher priority. That is, the resolution of a region of a relatively low priority may be controlled to be low.
The first field-of-view region or the region of higher priority may be determined using AI. The AI may be a model configured to estimate the angle of the gaze and the distance to a target object located in the gaze direction from images of the eyeball by using, as teaching data, images of the eyeball and the actual gaze direction of the eyeball in the images. The AI program may be stored in the display apparatus, the imaging apparatus, or an external apparatus. When the AI program is stored in the external apparatus, the AI program is transmitted through communication to the display apparatus.
In the instance of controlling the display on the basis of visual recognition detection, smart glasses further including an imaging apparatus that images an external image can be applied. The smart glasses are capable of displaying the imaged external information in real time.
As described above, using an apparatus that uses the organic light-emitting element according to the present embodiment enables stable display with good image quality even for a long time to be realized.
The present disclosure will be described below with reference to the examples. However, the present disclosure is not limited to these.
A 100-ml eggplant flask was charged with reagents and solvents described below.
Compound m-1: 1.0 g (2.7 mmol)
Compound m-2: 0.2 g (3.3 mmol)
Acetic acid: 20 ml
The reaction solution was subjected to heat-reflux-agitation in a nitrogen gas stream and agitation was performed for 6 hours. Subsequently, acetic acid was added, and reflux-agitation was performed for 6 hours in a nitrogen gas stream. After the reaction was completed, water and toluene were added and liquid separation was performed. Thereafter, a toluene solution was concentrated and slurry washing with methanol was performed so as to obtain 0.69 g (yield: 65%) of yellow solid Compound m-3.
A 100-ml eggplant flask was charged with reagents and solvents described below.
Compound m-3: 0.5 g (1.3 mmol)
Compound m-4: 0.9 g (2.8 mmol)
Pd(PPh3)4: 0.05 g
2M-Sodium carbonate aqueous solution: 8 ml
The reaction solution was subjected to heat-reflux-agitation in a nitrogen gas stream and agitation was performed for 6 hours. After the reaction was completed, water and toluene were added and liquid separation was performed. This was refined through column chromatography (toluene:heptane) and recrystallized with toluene so as to obtain 0.6 g (yield: 80%) of light-yellow solid Compound m-5.
(3) Synthesis of Exemplary compound A4
A 200-ml eggplant flask was charged with reagents and solvents described below.
Compound m-5: 0.4 g (0.65 mmol)
Compound m-6: 0.3 g (1.4 mmol)
Potassium phosphate: 0.34 g
The reaction solution was subjected to heat-reflux-agitation in a nitrogen gas stream and agitation was performed for 6 hours. After the reaction was completed, filtration was performed, and dissolution into xylene and silica gel adsorption washing were performed. Thereafter, the solvent was concentrated, slurry washing with methanol was performed, and filtration was performed so as to obtain 0.45 g (yield: 81%) of white solid Exemplary compound A4.
Exemplary compound A4 was subjected to mass analysis by using MALDI-TOF-MS (Autoflex LRF produced by Bruker).
measured value: m/z=867, calculated value: C64H38N2O2=867
As presented in Table 4 and Table 5, exemplary compounds in Examples 2 to 20 were synthesized in the manner akin to that in Example 1 except that the raw materials m-2 and m-6 in Example 1 were changed. In this regard, the measured values of m/z measured in the manner akin to that in Example 1 are presented.
An organic light-emitting element having a bottom emission type structure in which an anode, a hole injection layer, a hole transport layer, an electron blocking layer, a light-emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode were successively formed was produced.
An ITO film was formed on a glass substrate, and a predetermined patterning was performed so as to form an ITO electrode (anode). At this time, the film thickness of the ITO electrode was set to be 100 nm. The substrate provided with the thus formed ITO electrode was used as an ITO substrate in the steps below. Subsequently, an organic compound layer and an electrode layer presented in Table 6 were continuously formed on the above-described ITO substrate by performing vacuum vapor deposition due to resistance heating in a vacuum chamber at 1.33×10−4 Pa. In this regard, the electrode area of the opposite electrode (metal electrode layer, cathode) was set to be 3 mm2.
Regarding the resulting element, the characteristics of the element were measured and evaluated. The maximum emission wavelength of the light-emitting element was 522 nm, and the maximum external quantum efficiency (E.Q.E.) was 1.3 where that of Comparative example 1 was assumed to be 1.0. Further, a continuous driving test at a current density of 100 mA/cm2 was performed, and a time when the luminance deterioration rate reached 5% (LT95) was measured. As a result, the ratio of luminance deterioration rate was 1.4 where that of Comparative example 1 was assumed to be 1.0. In the present example, regarding the specific measuring apparatus, the current-voltage characteristics were measured using a microammeter 4140B produced by Hewlett-Packard Company, and the emission luminance was measured using BM7 produced by TOPCON CORPORATION.
Organic light-emitting elements were produced in the manner akin to that in Example 21 except that compounds were appropriately changed to the compounds presented in Table 7. Regarding the resulting elements, the characteristics of the elements were measured and evaluated in the manner akin to that in Example 21. The measurement results are presented in Table 7. In this regard, Comparative compound 1-A used as the host material in Comparative example 1 is Compound 1-A described in US 2014/0034925.
As presented in Table 7, the maximum external quantum efficiency (E.Q.E.) of each example was more than 1.0 relative to that of Comparative example 1, and, therefore, the light-emitting elements of the examples have higher light emission efficiency. The cause of this is due to the compounds according to the present embodiment having larger S1 and T1. In addition, the light-emitting elements according to the examples had longer life. The cause of this is due to the compounds according to the present embodiment having more excellent film performance and sublimation properties. Consequently, using the compounds according to the present embodiment enables the element having higher efficiency and excellent durability characteristics to be provided.
An organic light-emitting element was produced in the manner akin to that in Example 21 except that the organic compound layer and the electrode layer presented in Table 8 were continuously produced.
Regarding the resulting element, the characteristics of the element were measured and evaluated. The emission color of the light-emitting element was green. In addition, a time when the luminance deterioration rate reached 5% (LT95) was measured in the manner akin to that in Example 21. As a result, the ratio of luminance deterioration rate was 1.8 where that of Comparative example 2 was assumed to be 1.0.
Organic light-emitting elements were produced in the manner akin to that in Example 42 except that compounds were appropriately changed to the compounds presented in Table 9. Regarding the resulting elements, the characteristics of the elements were measured and evaluated in the manner akin to that in Example 42. The measurement results are presented in Table 9.
The organic compound according to the present disclosure has large S1 and T1, has excellent film performance and sublimation properties, and is a compound suitable for the organic light-emitting element. Consequently, using the organic compound according to the present disclosure as a constituent material of an organic light-emitting element enables the organic light-emitting element having favorable light emission characteristics and durability characteristics to be obtained.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2021-187046, filed Nov. 17, 2021, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-187046 | Nov 2021 | JP | national |
