Patent Application
20090230857
This application claims the benefit of Korean Patent Application No. 10-2008-0024097, filed on Mar. 14, 2008 and Korean Patent Application No. 10-2008-0090500, filed on Sep. 12, 2008, the disclosures of which are each hereby incorporated by reference herein in their entireties.
1. Technical Field
The present disclosure relates to an aromatic heterocyclic compound, an organic light emitting diode including an organic layer comprising the aromatic heterocyclic compound, and to a method of manufacturing the organic light emitting diode. More particularly, the present disclosure relates to an aromatic heterocyclic compound that has beneficial light emitting properties, and is used to manufacture an organic light emitting diode which can operate at a low voltage, and have high efficiency, high luminance, high color purity and long lifetime, an organic light emitting diode including an organic layer comprising the aromatic heterocyclic compound, and to a method of manufacturing the organic light emitting diode.
2. Description of the Related Art
Organic light emitting diodes (OLEDS) may have good luminance, operating voltage and response time and can realize multicolor images. In this regard, much research has been conducted on OLEDs.
In general, OLEDs have a stacked structure of an anode, an organic emissive layer, and a cathode. OLEDs may also have various structures such as, for example, anode/hole injection layer/hole transport layer/emissive layer/electron transport layer/electron injection layer/cathode, anode/hole injection layer/hole transport layer/emissive layer/hole blocking layer/electron transport layer/electron injection layer/cathode, or the like.
The materials used in OLEDs can be classified into, for example, either vacuum deposition materials or solution coating materials according to a method of forming an organic layer. When manufacturing an OLED using a vacuum deposition process, the use of a vacuum system and a shadow mask to form pixels for a natural color display may be required. On the other hand, in the case of manufacturing an OLED using a solution coating process such as, for example, inkjet printing, screen printing, or spin coating, it may be relatively easy to prepare an organic layer, manufacturing costs may be low, and a relatively good resolution can be achieved as compared to the case of using a shadow mask.
Therefore, there is still a need to develop a compound having high thermal stability and light-emitting properties, and which can be used to form an organic layer of an organic light emitting diode, regardless of the method used for forming the organic layer.
In accordance with an exemplary embodiment of the present invention, an aromatic heterocyclic compound represented by Formula 1 as set forth below is provided:
wherein R1 through R9 are each independently hydrogen, halogen, a cyano group, a nitro group, a hydroxyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C5-C20 cycloalkyl group, a substituted or unsubstituted C5-C20 cycloalkenyl group, a substituted or unsubstituted C5-C20 aryl group, a substituted or unsubstituted C2-C30 heteroaryl group, or a group represented by —N(Z1)(Z2) where Z1 and Z2 are each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C5-C20 aryl group,
R10 through R12 are each independently hydrogen, halogen, a cyano group, a nitro group, a hydroxyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C5-C20 cycloalkyl group, a substituted or unsubstituted C5-C20 cycloalkenyl group, a substituted or unsubstituted C5-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, a group represented by —N(Z1)(Z2) where Z1 and Z2 are each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C5-C20 aryl group, or a group represented by -Q1-Q2 where Q1 is a C5-C20 arylene group or a C2-C20 heteroarylene group, and Q2 is a substituted or unsubstituted C5-C20 aryl group or a substituted or unsubstituted C2-C20 heteroaryl group,
a, b, and c are each independently 0, 1 or 2; and
X is CY1 or N, wherein Y1 is hydrogen, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C1-C20 alkoxy group.
In accordance with an exemplary embodiment of the present invention, an organic light emitting diode is provided. The organic light emitting diode comprising a first electrode, a second electrode, and an organic layer comprising the aromatic heterocyclic compound described above between the first electrode and the second electrode.
In accordance with an exemplary embodiment of the present invention, a method of manufacturing an organic light emitting diode is provided. The method comprising forming a first electrode on a substrate, forming an organic layer comprising the aromatic heterocyclic compound described above on the first electrode and forming a second electrode on the organic layer.
Exemplary embodiments of the present invention can be understood in more detail from the following description taken in conjunction with the attached drawings in which:
The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown.
Exemplary embodiments of the present invention provide an aromatic heterocyclic compound represented by Formula 1 below:
wherein R10 through R12 may be, for example, each independently hydrogen, halogen, a cyano group, a nitro group, a hydroxyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C5-C20 cycloalkyl group, a substituted or unsubstituted C5-C20 cycloalkenyl group, a substituted or unsubstituted C5-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, a group represented by —N(Z1)(Z2) where Z1 and Z2 are each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C5-C20 aryl group, or a group represented by -Q1-Q2 where Q1 is a C5-C20 arylene group or a C2-C20 heteroarylene group, and Q2 is a substituted or unsubstituted C5-C20 aryl group or a substituted or unsubstituted C2-C20 heteroaryl group.
R10 through R12 as described above may each independently exist in the position as indicated in Formula 1A below:
For example, R10 through R12 may be each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C5-C20 aryl group, a substituted or unsubstituted C2-C20 heteroaryl group, or a group represented by -Q1-Q2 where Q1 is a C5-C20arylene group, and Q2 is a substituted or unsubstituted C5-C20 aryl group, or a substituted or unsubstituted C2-C20 heteroaryl group, and more particularly, R10 through R12 may be, for example, each independently hydrogen, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C5-C14 aryl group, a substituted or unsubstituted C2-C14 heteroaryl group, or a group represented by -Q1-Q2 where Q1 is a C5-C14 arylene group, and Q2 is a substituted or unsubstituted C5-C14 aryl group, or a substituted or unsubstituted C2-C14heteroaryl group.
Substituents of R10 through R12 as described above may include, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an amino group, an amidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1-C10 alkyl group, a C1-C10 alkoxy group, a C6-C20 aryl group, and a C2-C20 heteroaryl group, but the exemplary embodiments of the present invention are not limited thereto. For example, substituents of R10 through R12 may include a C1-C10 alkyl group and a C6-C20 aryl group.
In Formula 1, a, b, and c may be, for example, each independently 0, 1, or 2.
For example, R10 through R12 of Formula 1 may be each independently hydrogen or one of the structures represented by Formula 2a to 2o below, but the exemplary embodiments of the present invention are not limited thereto:
In Formula 1, X is CY1 or N, wherein Y1 is hydrogen, a substituted or unsubstituted C1-C20 alkyl group or a substituted or unsubstituted C1-C20 alkoxy group.
Substituents of Y1 as described above may include, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an amino group, an amidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1-C10 alkyl group, a C1-C10 alkoxy group, a C6-C20 aryl group, and a C2-C20 heteroaryl group, but the present invention is not limited thereto. For example, substituents of Y1 may include a C1-C10 alkyl group or a C6-C20 aryl group.
For example, Y1 may be a substituted or unsubstituted C1-C10 alkyl group or a substituted or unsubstituted C1-C10 alkoxy group.
According to an exemplary embodiment of the present invention, an aromatic heterocyclic compound may be represented by Formula 1 where X is CH or N, but the exemplary embodiments of the present invention are not limited thereto.
In Formula 1, R1 through R9 may be, for example, each independently hydrogen, halogen, a cyano group, a nitro group, a hydroxyl group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C5-C20 cycloalkyl group, a substituted or unsubstituted C5-C20 cycloalkenyl group, a substituted or unsubstituted C5-C20 aryl group, a substituted or unsubstituted C2-C30 heteroaryl group, or a group represented by —N(Z1)(Z2) where Z1 and Z2 may be each independently hydrogen, a substituted or unsubstituted C1-C20 alkyl group, or a substituted or unsubstituted C5-C20 aryl group.
Substituents of R1 through R9 as described above may include, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an amino group, an amidino group, hydrazine, hydrazone, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, a phosphoric acid or a salt thereof, a C1-C10 alkyl group, a C1-C10 alkoxy group, a C6-C20 aryl group, and a C2-C20 heteroaryl group, but the present invention is not limited thereto. For example, substituents of R1 through R9 may include a C1-C10 alkyl group or a C6-C20 aryl group.
For example, R1 through R9 may be each independently hydrogen, a substituted or unsubstituted C5-C20 aryl group, or a substituted or unsubstituted C2-C30 heteroaryl group. For example, when R1 through R9 are each independently hydrogen, a substituted or unsubstituted C5-C20 aryl group, or a substituted or unsubstituted C2-C30 heteroaryl group, an organic layer comprising the aromatic heterocyclic compound of Formula 1 can have improved film-forming ability and increased stability. For example, R1 through R9 may be each independently hydrogen, a substituted or unsubstituted C5-C14 aryl group, or a substituted or unsubstituted C2-C14 heteroaryl group.
For example, R1 through R4 and R6 through R9 are hydrogen, R5 is hydrogen, a substituted or unsubstituted C5-C20 aryl group, or a substituted or unsubstituted C2-C30 heteroaryl group, but the present invention is not limited thereto.
For example, R1 through R9 may be each independently hydrogen or one of the structures represented by Formula 3a to 3i below, but the exemplary embodiments of the present invention are not limited thereto:
For example, the aromatic heterocyclic compound according to exemplary embodiments of the present invention may be represented by Formula 1B below:
wherein R10 through R12 and X are the same as defined above.
In
Examples of the unsubstituted C1-C20 alkyl group used herein include but are not limited to methyl, ethyl, propyl, isobutyl, sec-butyl, pentyl, iso-amyl, hexyl, and the like. At least one hydrogen atom of the alkyl group described above can be substituted with, for example, a halogen atom, a hydroxyl group, a nitro group, a cyano group, an amino group, an amidino group, hydrazine, hydrazone, a carboxyl group or salts thereof, a sulfonic acid group or salts thereof, a phosphoric acid or salts thereof, a C1-C30 alkyl group, a C1-C30 alkoxy group, a C1-C30 alkenyl group, a C1-C30 alkynyl group, a C6-C30 aryl group, or a C2-C20 heteroaryl group.
Examples of the unsubstituted C1-C20 alkoxy group used herein include but are not limited to methoxy, ethoxy, propoxy, and the like. At least one hydrogen atom of the alkoxy group can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
The unsubstituted C2-C20 alkenyl group used herein contains a carbon-carbon double bond in the middle or end of the alkyl group defined above. Examples of the unsubstituted C2-C20 alkenyl group include but are not limited to ethylene, propylene, butylene, hexylene and the like. At least one hydrogen atom of the alkenyl groups can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
The unsubstituted C2-C20 alkynyl group used herein contains a carbon-carbon triple bond in the middle or end of the alkyl group defined above. At least one hydrogen atom of the alkynyl groups can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above. Examples of the unsubstituted C2-C20 alkynyl group include but are not limited to acetylene, propylene, phenylacetylene, naphthylacetylene, isopropylacetylene, t-butylacetylene, diphenylacetylene, and the like.
The unsubstituted C5-C20 aryl group refers to a C5-C20 carbocyclic aromatic system containing at least one aromatic ring. At least two aromatic rings can be fused with each other, or bound to each other by a single bond, or the like. At least one hydrogen atom of the aryl groups can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
The substituted or unsubstituted C5-C20 aryl group can be, for example, a phenyl group, a C1-C10 alkylphenyl group (for example, an ethylphenyl group), a halophenyl group (for example, o-, m- and p-fluorophenyl groups and a dichlorophenyl group), a cyanophenyl group, a dicyanophenyl group, a trifluoro methoxy phenyl group, a biphenyl group, a halobiphenyl group, a cyanobiphenyl group, a C1-C10 biphenyl group, a C1-C10 alkoxybiphenyl group, o-, m-, and p-tolyl groups, o-, m- and p-cumenyl group, a mesityl group, a phenoxy phenyl group, a (α,α-dimethylbenzene)phenyl group, a (N,N′-dimethyl)aminophenyl group, a (N,N′-diphenyl)aminophenyl group, a pentalenyl group, an indenyl group, a naphthyl group, a halonaphthyl group (for example, a fluoronaphthyl group), a C1-C10 alkylnaphthyl group (for example, a methylnaphthyl group), a C1-C10 alkoxynaphthyl group (for example, a methoxynaphthyl group), a cyanonaphthyl group, an anthracenyl group, an azulenyl group, or the like. These aryl group can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
The unsubstituted C5-C20 arylene group used herein is a bivalent linker having a structure similar to that of the unsubstituted C5-C20 aryl group, and examples thereof include a phenylene group, a naphthylene group, and the like. However, exemplary embodiments of the present invention are not limited thereto. At least one hydrogen atom of the arylene group can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
The unsubstituted C2-C20 heteroaryl group refers to a system comprising at least one aromatic ring that includes at least one hetero atom selected from N, O, P, and S and the remaining ring member is carbon. The one or more aromatic rings can be fused with each other, or bound to each other by a single bond, or the like. At least one hydrogen atom of the heteroaryl groups can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
Examples of the unsubstituted C2-C20 heteroaryl group may include but are not limited to a pyrazolyl group, an imidazolyl group, an oxazolyl group, a thiazolyl group, a triazolyl group, a tetrazolyl group, an oxadiazolyl group, a pyridinyl group, a pyridazinyl group, a pyrimidinyl group, a triazinyl group, a carbazolyl group, an indolyl group, a quinolinyl group, an isoquinolinyl group, and the like. These heteroaryl groups can be substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
The unsubstituted C5-C20 cycloalkyl group refers to an alkyl group having a ring system, and the unsubstituted C5-C20 cycloalkenyl group refers to an alkenyl group having a ring system. At least one hydrogen atom of the cycloalkyl group and the cycloalkenyl group can be each independently substituted with, for example, the same substituents as those of the substituted C1-C20 alkyl group described above.
According to an exemplary embodiment of the present invention, the aromatic heterocyclic compound of Formula 1 may be one of Compounds 1 through 17 below, but the exemplary embodiments of the present invention are not limited thereto:
The aromatic heterocyclic compound of Formula 1 may be synthesized using, for example, organic synthesis.
The aromatic heterocyclic compound of Formula 1 as described above may be included in an organic layer of an organic light emitting diode. Thus, exemplary embodiments of the present invention also provide an organic light emitting diode including a first electrode, a second electrode, and an organic layer that is disposed between the first electrode and the second electrode, and includes the aromatic heterocyclic compound of Formula 1 as described above.
For example, the organic layer may be an emissive layer or an electron transporting layer.
The organic layer comprising the aromatic heterocyclic compound of Formula 1 may be formed using various known methods. For example, the organic layer may be formed by vacuum deposition or solution coating, such as spin coating, inkjet printing, screen printing, casting, Langmuir Blodgett (LB), spray printing, or the like. In addition, the organic layer comprising the aromatic heterocyclic compound of Formula 1 may be formed, for example, on a donor film using vacuum deposition or solution coating as described above, and then thermally transferred to a substrate on which a first electrode, and the like are formed. The aromatic heterocyclic compound of Formula 1 has beneficial solubility and thermal stability and can also be used to form a stable organic layer. Thus, an organic light emitting diode which can operate at low voltage, and have high efficiency and high luminance can be obtained.
The organic light emitting diode of exemplary embodiments of the present invention may further include, between the first electrode and the second electrode, at least one layer selected from the group consisting of a hole injection layer, a hole transport layer, an emissive layer, a hole blocking layer, an electron transport layer, and an electron injection layer. For example, the structures of organic light emitting diodes according to embodiments of the present invention are illustrated in
Hereinafter, a method of manufacturing an organic light emitting diode, according an exemplary embodiment of the present invention, will be described with reference to the organic light emitting diode illustrated in
First, a first electrode is formed by, for example, depositing or sputtering a high work-function material for a first electrode on a substrate. The first electrode can be an anode. The substrate, which can be any substrate that is used in conventional organic light emitting diodes, may be, for example, a glass substrate or a transparent plastic substrate that has excellent mechanical strength, thermal stability, transparency, and surface smoothness, can be easily treated, and is waterproof. The first electrode can be formed of, for example, ITO, indium zinc IZO, SnO2, ZnO, or any transparent material which has high conductivity.
Next, a hole injection layer (HIL) may be formed on the first electrode by, for example, vacuum deposition, spin coating, casting, Langmuir Blodgett (LB) deposition, or the like.
When the HIL is formed by vacuum deposition, vacuum deposition conditions may vary according to the compound that is used to form the HIL, and the desired structure and thermal properties of the HIL to be formed. In general, however, the vacuum deposition may be performed, for example, at a deposition temperature of about 100 to about 500° C., a pressure of about 10−8 to about 10−3 torr, and a deposition speed of about 0.01 to about 100 Å/sec.
When the HIL is formed by spin coating, coating conditions may vary according to the compound that is used to form the HIL, and the desired structure and thermal properties of the HIL to be formed. In general, however, the coating speed may be in a range of, for example, about 2,000 to about 5,000 rpm, and a temperature for heat treatment, which is performed to remove a solvent after coating, may be in a range of, for example, about 80 to about 200° C.
The HIL can be formed of any known materials used to form a HIL. For example, the material may m-MTDATA 4,4′,4″-tris(3-methylphenylphenylamino)triphenylamine), NPB (N,N′-di(1-naphthyl)-N,N′-diphenyl benzidine), TDATA, 2T-NATA, polyaniline/Dodecylbenzenesulfonic acid (Pani/DBSA); poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS); polyaniline/camphor sulfonic acid (Pani/CSA); (polyaniline)/poly(4-styrenesulfonate) (PANI/PSS); or the like.
The thickness of the HIL may be in the range of, for example, about 100 to about 10,000 Å, and particularly, in the range of about 100 to about 1,000 Å. When the thickness of the HIL is within the ranges described above, a satisfactory hole injecting ability of the HIL can be obtained without a substantial decrease in a driving voltage of the organic light emitting diode.
Next, a hole transport layer (HTL) may be formed on the HIL by, for example, vacuum deposition, spin coating, casting, LB deposition, or the like. When the HTL is formed by vacuum deposition or spin coating, the conditions for deposition and coating are similar to those for the formation of the HIL, although conditions for the deposition and coating may vary according to the compound that is used to form the HTL.
The HTL may be formed of any known materials used to form a HTL. For example, the HTL may be formed of a carbazole derivative, such as N-phenylcarbazole, polyvinylcarbazole, or the like; a typical amine derivative having an aromatic condensation ring such as N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl benzydine (α-NPD), triphenylamin-based material such as TCTA (4,4′,4″-tris(N-carbazolyl)triphenylamine); or the like.
The thickness of the HTL may be in a range of, for example, about 50 to about 1,000 Å, and particularly, in a range of about 100 to about 800 Å. When the thickness of the HTL is within the ranges described above, a satisfactory hole transporting ability of the HTL can be obtained without a substantial decrease in a driving voltage of the organic light emitting diode.
Next, an emissive layer (EML) may be formed on the HTL by, for example, vacuum deposition, spin coating, casting, LB deposition, or the like. When the EML is formed by vacuum deposition or spin coating, the conditions for deposition and coating are similar to those for the formation of the HIL, although the conditions for deposition and coating may vary according to the compound that is used to form the EML.
The EML may comprise the aromatic heterocyclic compound of Formula 1 according to the present invention, as described above. Herein, the aromatic heterocyclic compound of Formula 1 may be used, as a dopant, together with a know host material, and the EML may further comprise a known dopant material. In addition, the aromatic heterocyclic compound of Formula 1 may be used as a host. Alternatively, the aromatic heterocyclic compound of Formula 1 may be used alone. The host material may be, for example, Alq3, 4,4′-N,N′-dicarbazole-biphenyl (CBP), poly(n-vinylcarbazole) (PVK), 9,10-di(naphthyl)anthracene (AND), or the like, but the present invention is not limited thereto.
A known red dopant may be PtOEP, Ir(piq)3, Btp2Ir(acac), DCJTB, or the like, but the present invention is not limited thereto.
In addition, a known green dopant may be Ir(ppy)3 (ppy=phenylpyridine), Ir(ppy)2(acac), Ir(mpyp)3, C545T, or the like, but the present invention is not limited thereto.
A known blue dopant may be F2Irpic, (F2ppy)2Ir(tmd), Ir(dfppz)3, ter-fluorene, 4,4′-bis(4-diphenylaminostyryl)biphenyl (DPAVBi), 2,5,8,11-tetra-tert-butylperylene (TBP), or the like, but the present invention is not limited thereto.
When the dopant and the host are used together, the doping concentration of the dopant is not particularly limited. In general, however, the amount of the dopant may be in a range of, for example, about 0.01 to about 15 parts by weight based on 100 parts by weight of the host.
The thickness of the EML may be in a range of, for example, about 100 to about 1,000 Å, and particularly, in a range of about 200to about 600 Å. When the thickness of the EML is within the ranges described above, the EML can have beneficial light emitting properties without a substantial decrease in a driving voltage of the organic light emitting diode.
When the EML includes a phosphorous dopant, to prevent triplet excitons or holes from migrating into an electron transport layer (ETL), a hole blocking layer (HBL) may be formed between the ETL and the EML by, for example, vacuum deposition, spin coating, casting, LB deposition, or the like. When the HBL is formed by vacuum deposition or spin coating, the conditions for deposition and coating are similar to those for the formation of the HIL, although the conditions for deposition and coating may vary according to the compound that is used to form the HBL. Here, a material used to form the HBL can be any known material used to form a HBL. Examples of such material may include but are not limited to oxadiazol derivatives, triazol derivatives, phenanthroline derivatives, and the like.
The thickness of the HBL may be in a range of, for example, about 50 to about 1,000 Å, and preferably, in a range of about 100 to about 300 Å. When the thickness of the HBL is within the ranges described above, the EML can have beneficial hole blocking properties without a substantial decrease in a driving voltage of the organic light emitting diode.
Next, an electron transport layer (ETL) is formed on the EML or HBL by, for example, vacuum deposition, spin coating, casting, or the like. When the ETL is formed by vacuum deposition or spin coating, the conditions for deposition and coating are, in general, similar to those for the formation of the HIL, although the conditions for deposition and coating may vary according to the material that is used to form the ETL. The material used to form the ETL should be able to stably transport electrons injected from an electron injecting electrode (cathode), and may be the aromatic heterocyclic compound of Formula 1 as described above. In addition, a known electron transporting material, such as, for example, a quinoline derivative, in particular, tris(8-quinolinorate)aluminum (Alq3), TAZ, Balq, or the like can be used to form the ETL, but the exemplary embodiments of the present invention are not limited thereto.
The thickness of the ETL may be in a range of, for example, about 100 to about 1,000 Å, and preferably, in a range of about 150 to about 500 Å. When the thickness of the ETL is within the ranges described above, satisfactory electron transporting properties of the ETL can be obtained without a substantial decrease in a driving voltage of the organic light emitting diode.
In addition, an electron injection layer (EIL) that makes it relatively easy for electrons to be injected from a cathode may be formed on the ETL, and a material used to form the EIL is not particularly limited.
The material used to form the EIL may be the aromatic heterocyclic compound of Formula 1 as described above. In addition, a known material, such as, for example, LiF, NaCl, CsF, Li2O, BaO, or the like can be used as the material used to form the EIL. The conditions for deposition are, in general, similar to those for the formation of the HIL, although the conditions for deposition may vary according to the compound used to form the EIL.
The thickness of the EIL may be in a range of, for example, about 1 to about 100 Å, and particularly, in a range of about 5 to about 50 Å. When the thickness of the EIL is within the ranges described above, the EIL can have satisfactory electron injecting properties without a substantial decrease in a driving voltage of the organic light emitting diode.
Finally, a second electrode may be formed on the EIL by, for example, vacuum deposition, sputtering, or the like. The second electrode can be used as a cathode. The second electrode may be formed of, for example, a low work-function metal, an alloy, an electrically conductive compound, or a combination thereof. For example, the second electrode may be formed of Li, Mg, Al, Al—Li, Ca, Mg—In, Mg—Ag, or the like. Alternatively, a transparent cathode formed of, for example, ITO or IZO can be used to produce a front surface light emitting diode.
The method of manufacturing an organic light emitting diode, according to an exemplary embodiment of the present invention, includes: forming a first electrode on the substrate; forming an organic layer comprising the aromatic heterocyclic compound of Formula 1 on the first electrode; and forming a second electrode on the organic layer. Herein, the organic layer may be an EML, a HIL, a HTL, a HBL, or ETL. In addition, the manufacturing method of the organic light emitting diode may further include, if necessary, forming at least one layer selected from the group consisting of, for example, the HIL, the HTL, the EML, the HBL, the ETL, and an EIL.
The forming of the organic layer comprising the aromatic heterocyclic compound of Formula 1 may be performed by, for example, vacuum deposition or solution coating such as spin coating, inkjet printing, screen printing, casting, LB, or spray printing. In addition, the organic layer comprising the aromatic heterocyclic compound of Formula 1 may be formed, for example, on a donor film using vacuum deposition or solution coating as described above, and then thermally transferred to a substrate on which a first electrode and the like are formed.
Hereinafter, Synthesis Examples and Examples of the present invention will be described in detail. However, these examples are provided to facilitate the understanding of the present invention only, and are not intended to limit the scope of the present invention.
Compound 1 was synthesized through Reaction Scheme 1 below:
about 3 g of 5-(3-bromophenyl)-5H-pyrido[3,2-b]indole (about 9.28 mmol), about 4.24 g of 2-(9-phenylanthracen-10-yl)-4,4,5,5-tetramethyl-[1,3,2]-dioxaborolane) (about 11.14 mmol), and about 0.54 g of tetrakis(triphenylphosphine)palladium[0] (about 0.464 mmol) were dissolved in about 60 ml of THF, and about 20 ml of an aqueous sodium carbonate solution (about 11.14 mmol) was added to the mixture. Then, the mixture was refluxed for about 24 hours. After reflux, the resultant was extracted using methylene chloride, and a column chromatography was performed on the resultant to obtain about 3.9 g of 5-(3-(10-phenylanthracen-9-yl)phenyl)-5H-pyrido[3,2-b]indole (yield about 84.6%).
1H NMR (about 300 MHz, CDCl3) δ about 7.30-about 7.89 (m, about 22H), about 8.47 (d, J=about 7.6 Hz, about 1H), about 8.62 (d, J =about 4.7 Hz, about 1H)
Thermal analysis of Compound 1 was performed using thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) (N2 atmosphere, temperature range: room temperature to about 600° C. (about 10° C./min)-TGA, room temperature to about 400° C.-DSC, Pan Type: Pt Pan in disposable Al Pan (TGA), disposable Al pan (DSC)). As a result, it was confirmed that Compound 1 had a Tg of about 117° C., a Tm of about 279° C., and a Td of about 331° C.
Also, the HOMO of Compound 1 had an energy of about −5.249 eV, the LUMO of Compound 1 had an energy of about −1.767 eV, and an energy gap between the HOMO and LUMO was about 3.482 eV (the values described above are calculated values). On the other hand, the HOMO of Compound 1 had an energy of about −5.89 eV, the LUMO of Compound 1 had an energy of about −2.90 eV, and an energy gap between the HOMO and LUMO was about 2.99 eV (the values described above are actually measured values from AC2 and UV edge).
Compound 6 was synthesized through Reaction Scheme 2 below:
about 1.6 g of 5-(3-bromophenyl)-5H-pyrido[3,2-b]indole (about 4.93 mmol), about 3 g of 4,4,5,5-tetramethyl-2-(10-(3-(naphthalen-2-yl) phenyl)anthracen-9-yl)-1,3,2-dioxaborolane (about 5.92 mmol), and about 0.29 g of tetrakis(triphenylphosphine)palladium[0] were dissolved in about 50 ml of THF, and about 15 ml of an aqueous sodium carbonate solution (about 5.92 mmol) was added to the mixture. Then, the mixture was refluxed for about 24 hours. After reflux, the resultant was extracted using methylene chloride, and a column chromatography was performed on the resultant to obtain about 2.7 g of 5-(3-(10-(3-(naphthalen-2-yl)phenyl)anthracen-9-yl)phenyl)-5H-pyrido[3,2-b]indole (yield about 88%).
1H NMR (about 300 MHz, CDCl3) δ about 7.38-about 7.96 (m, about 28H), about 8.14 (d, J=about 9.4 Hz, about 1H), about 8.63 (d, J=about 4.8 Hz, about 1H)
Thermal analysis of Compound 6 was performed using TGA and DSC (N2 atmosphere, temperature range: room temperature to about 600° C. (about 10° C./min)-TGA, room temperature to about 400° C.-DSC, Pan Type: Pt Pan in disposable Al Pan (TGA), disposable Al pan (DSC)). As a result, it was confirmed that Compound 6 had a Tg of about 137° C., a Tm of about 286° C., and a Td of about 483° C.
In addition, the LUMO of Compound 6 had an energy of about −1.774 eV, the HOMO of Compound 6 had an energy of about −5.250 eV, and an energy gap between the LUMO and HOMO was about 3.475 eV (the values described above are calculated values).
Compound 7 was synthesized through Reaction Scheme 3 below:
about 4.73 g of 5-(3-bromophenyl)-5H-pyrido[3,2-b]indole (about 14.63 mmol), about 7.56 g of 4,4,5,5-tetramethyl-2-(10-(3-(naphthalen-2-yl)phenyl)anthracen-9-yl)-1,3,2-dioxaborolane (about 17.56 mmol), and about 0.84 g of tetrakis(triphenylphosphine)palladium[0] (0.73mmol) were dissolved in about 90 ml of THF, and about 30 ml of an aqueous sodium carbonate solution (about 17.56 mmol) was added to the mixture. Then, the mixture was refluxed for about 24 hours. After reflux, the resultant was extracted using methylene chloride, and a column chromatography was performed on the resultant to obtain about 5.6 g of 5-(3-(10-(naphthalen-2-yl)anthracen-9-yl)phenyl)-5H-pyrido[3,2-b]indole (yield about 70.0%).
1H NMR (about 300 MHz, CDCl3) δ about 7.26 to about 7.47 (m, about 6H), about 7.58 to about 8.11 (m, about 19H), about 8.6 (d, J=about 11.2 Hz, about 1H)
Thermal analysis of Compound 7 was performed using TGA and DSC (N2 atmosphere, temperature range: room temperature to 600° C. (10° C./min)-TGA, room temperature to 400° C.-DSC, Pan Type: Pt Pan in disposable Al Pan (TGA), disposable Al pan (DSC)). As a result, it was confirmed that Compound 7 had a Tg of 139° C., a Tm of 344° C., and a Td of 447° C.
In addition, the LUMO of Compound 7 had an energy of about −1.764 eV, the HOMO of Compound 7 had an energy of about −5.274 eV, and an energy gap between the LUMO and HOMO was about 3.511 eV (the values described above are calculated values).
Evaluation of light emitting properties of Compound 1 was performed by evaluating UV absorption and photoluminescence (PL) spectra of Compound 1.
Compound 1 was diluted in toluene to the concentration of about 0.2 mM, and then the UV absorption spectrum thereof was measured using a Shimadzu UV-350 Spectrometer. In addition, Compound 1 was diluted in toluene to the concentration of about 10 mM, and the PL spectrum thereof was measured using an ISC PC1 spectrofluorometer equipped with a Xenon lamp. As a result, it was confirmed that the maximum absorption wavelength of the UV absorption spectrum of Compound 1 was about 400 nm, and the maximum wavelength of the PL spectrum of Compound 1 was about 445 nm.
By using Compound 1 as a material used to form an emissive layer (EML), an organic light emitting diode having the following structure was manufactured: ITO//HIL(about 60 nm)//HTL(about 30 nm)//EML(about 35 nm)//ETL(about 25 nm)//LiF(about 0.6 nm)/Al(about 150 nm).
As an anode, an about 15 ΩD/cm2 (about 1000 Å) ITO glass substrate was cut to a size of about 50 mm×about 50 mm×about 0.7 mm, ultrasonic washed with acetone isopropyl alcohol and pure water for about 15 minutes each, and then washed with UV ozone for about 30 minutes. MTDATA as a material used to form a hole injection layer (HI L) was vacuum deposited on the ITO anode at a deposition speed of about 1 Å/sec to form the HIL having a thickness of about 60 nm, and then α-NPD was vacuum deposited on the HIL at a deposition speed of about 1 Å/sec to form a hole transport layer (HTL) having a thickness of about 30 nm. Then, Compound 1 was vacuum deposited on the HTL at a deposition speed of about 1 Å/sec to form an emissive layer (EML) having a thickness of about 35 nm. Subsequently, Alq3 was vacuum deposited on the EML to form an electron transport layer (ETL) having a thickness of about 25 nm. Then, LiF was vacuum deposited on the ETL to form an electron injection layer (EIL) having a thickness of about 0.6 nm, and Al was vacuum deposited on the EIL to form a cathode having a thickness of about 150 nm to complete the manufacture of an organic light emitting diode as illustrated in
An organic light emitting diode was manufactured in the same manner as in Example 1, except that the EML was formed using Compound 1 as a host and DPAVBi as a dopant (doping concentration of about 5 wt %), instead of using only Compound 1 as a material used to form the EML. This is referred to as Sample 2. Herein, Compound 1 (host) and DPAVBi (dopant) were respectively deposited at a deposition speed of about 1 Å/sec and at a deposition speed of about 0.05 Å/sec.
An organic light emitting diode was manufactured in the same manner as in Example 2, except that the HTL was formed to a thickness of about 20 nm. This is referred to as Sample 3.
An organic light emitting diode was manufactured in the same manner as in Example 2, except that the EML was formed of ADN (9, 10-dinaphthylanthracene) as a host and DPAVBi (doping concentration of about 5 wt %) as a dopant, instead of using Compound 1 as a host and DPAVBi as a dopant (doping concentration of about 5 wt %), and the ETL was formed of Compound 1, instead of using Alq3. This is referred to as Sample 4.
An organic light emitting diode was manufactured in the same manner as in Example 2, except that the EML was formed of ADN (9, 10-dinaphthylanthracene) as a host and DPAVBi (doping concentration of about 5 wt %) as a dopant, instead of using Compound 1 as a host and DPAVBi as a dopant (doping concentration of about 5 wt %). This is referred to as Sample A.
Turn-on voltage, power, luminance and color coordinate of each of Samples 1 through 4 and A were evaluated using a PR650 (Spectroscan) Source Measurement Unit. The results are shown in Table 2 below.
In addition, graphs (brightness, current density, efficiency and power efficiency) showing the evaluation results of Samples 1 through 4 and A (Examples 1 through 4 and Comparative Example 1) are illustrated in
Having described the exemplary embodiments of the present invention, it is further noted that it is readily apparent to those of reasonable skill in the art that various modifications may be made without departing from the spirit and scope of the invention which is defined by the metes and bounds of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2008-0024097 | Mar 2008 | KR | national |
| 10-2008-0090500 | Sep 2008 | KR | national |
