An organic light-emitting element including a cover layer and a compound for a cover layer applicable to the above organic light-emitting element

Abstract

The present invention relates to an organic light-emitting element including a cover layer and a compound for a cover layer applicable to the above organic light-emitting element, and provides an organic light-emitting element in which the above cover layer includes a compound having a refractive index of 2.26 or more at 450 nm and an attenuation coefficient value at 430 nm in a range greater than 0.10 and less than 0.17, and a compound for a cover layer applicable to the above organic light-emitting element.

Description

Technical Field

[0001] The present invention relates to an organic light-emitting device including a cover layer and a compound for a cover layer applicable to the above organic light-emitting device. Background Art

[0002] Recently, a self-luminous organic light-emitting device that can be driven at a low voltage has attracted much attention as a new generation of display device because it has advantages such as excellent viewing angle and contrast ratio compared with a liquid crystal display (LCD), which is the mainstream of flat display devices, does not require a backlight, can achieve light weight and thinness, consumes less power, and has a wide color reproduction range.

[0003] Materials used as organic layers in organic light-emitting diodes can generally be classified into light-emitting layer materials, hole injection materials, hole transport materials, electron transport materials, and electron injection materials according to their functions. In addition, the above light-emitting materials can be classified into polymers and single molecules according to their molecular weights, and can be classified into fluorescent materials derived from singlet excited states of electrons, phosphorescent materials derived from triplet excited states of electrons, and delayed fluorescent materials derived from electron transfer from triplet excited states to singlet excited states according to their light-emitting mechanisms. The light-emitting materials can be classified into blue, green, yellow, and orange-yellow light-emitting materials required to achieve better natural colors than red light-emitting materials according to their light-emitting colors. In addition, in order to improve color purity and light-emitting efficiency based on energy transfer, a host / dopant type material can also be used as a light-emitting substance. The principle is that by mixing a small amount of a light-emitting substance with an energy band gap smaller than that of the host, i.e., a dopant, into the light-emitting layer, excitons generated in the host can be transferred to the dopant and emit light. By means of the above principle, light of a desired wavelength can be obtained according to the types of the host and the dopant.

[0004] In addition, the efficiency of an organic light-emitting device can generally be divided into internal light-emitting efficiency and external light-emitting efficiency. The internal light-emitting efficiency is related to the efficiency of generating excitons and achieving light conversion in organic layers such as a hole transport layer, a light-emitting layer, and an electron transport layer between a first electrode and a second electrode. Theoretically, the internal light-emitting efficiency of fluorescence is 25%, and that of phosphorescence is 100%. In addition, the external light-emitting efficiency refers to the efficiency of extracting light generated in the organic layer to the outside of the organic light-emitting device. It is currently known that about 20% of the internal light-emitting efficiency can usually be extracted to the outside. As a method for improving the above light extraction efficiency, in order to prevent light irradiated to the outside from being lost due to total reflection, various organic compounds with a high refractive index are usually used as a cover layer, and in order to improve the performance of the organic light-emitting device, efforts have been made to develop an organic compound having a high refractive index and film stability capable of improving the external light-emitting efficiency.

[0005] Prior art documents

[0006] Patent documents

[0007] (Patent Document 1) Korean Patent Publication No. 10-2004-0098238 Summary of the invention

[0008] An object of the present invention is to provide an organic light-emitting device that can expand the absorption wavelength in the ultraviolet region and thereby ensure the stability of components when exposed to external ultraviolet rays, and at the same time minimize the absorption in the visible light region, by using a compound having a refractive index of 2.26 or more at 450 nm and an attenuation coefficient value greater than 0.10 and less than 0.17 at 430 nm as a material for a cover layer, thereby enabling high efficiency, high color purity, and a long service life.

[0009] As a means for solving the above problems

[0010] An embodiment of the present invention provides an organic light-emitting device, which is an organic light-emitting device including a cover layer, and the cover layer includes a compound having a refractive index of 2.26 or more at 450 nm and an attenuation coefficient value in the range of greater than 0.10 and less than 0.17 at 430 nm. Specifically, the refractive index of the compound at 450 nm may be 2.28 or more, and the attenuation coefficient value at 430 nm may be in the range of greater than 0.10 and less than 0.15. More specifically, the refractive index of the compound at 450 nm may be 2.30 or more, and the attenuation coefficient value at 430 nm may be in the range of greater than 0.10 and less than 0.13.

[0011] In addition, the attenuation coefficient value of the compound at 450 nm may be less than 0.01, and the attenuation coefficient value of the compound at 380 nm may be greater than 0.5.

[0012] In addition, the thickness of the cover layer may be 100 to

[0013] In addition, the compound may include a tertiary amine structure.

[0014] In addition, the organic light-emitting device may include a first electrode and a second electrode, and may include one or more blue light-emitting layers between the first electrode and the second electrode.

[0015] In addition, the present invention provides a compound for a cover layer, which is a compound for a cover layer of an organic light-emitting device, and is represented by the following Chemical Formula 1.

[0016] <Chemical Formula 1>

[0017]

[0018] In the above Chemical Formula 1, A, B, and C are each independently a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 50 carbon atoms. Any one or more of A, B, and C are represented by the following Chemical Formula 1-1 or Chemical Formula 1-2. L1 to L3 are each independently a direct bond, a substituted or unsubstituted arylene group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 50 carbon atoms.

[0019] <Chemical Formula 1-1>

[0020]

[0021] <Chemical Formula 1-2>

[0022]

[0023] In the above Chemical Formula 1-1 or Chemical Formula 1-2, Xs are each independently C, CR, N, O, S, NR, or CRR', where R and R' are each independently hydrogen, deuterium, a halogen, a nitro group, a nitrile group, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, a substituted or unsubstituted mercapto group having 1 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 50 carbon atoms.

[0024] Specifically, the compound for the cover layer may be any one of the following compounds.

[0025]

[0026] An organic light-emitting device including a cover layer according to an embodiment of the present invention can reduce total reflection and improve light-emitting efficiency by controlling the refractive index and attenuation coefficient of the cover layer, and can also extend the service life of the device.

[0027] Specifically, the light extraction effect can be improved and the high-efficiency effect can be achieved thereby by using a high refractive index compound having a refractive index of 2.26 or more at 450 nm as a material for the cover layer.

[0028] In addition, the absorption wavelength in the ultraviolet region can be expanded and the life improvement effect when exposed to external ultraviolet rays can be achieved thereby by using a compound having an attenuation coefficient k greater than 0.10 at 430 nm as a material for the cover layer.

[0029] In addition, the absorption wavelength in the blue visible light region can be minimized and high color purity can be achieved thereby by using a compound having an attenuation coefficient k value less than 0.17 at 430 nm as a material for the cover layer.

[0030] In addition, by using a compound having a condensed ring and a tertiary amino group as the material for the cover layer, a lower deposition temperature can be maintained and a higher glass transition temperature (Tg) can be formed, thereby improving the thermal stability of the compound when performing the deposition process.

[0031] Next, the above-described effects and additional effects will be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a cross-sectional view schematically illustrating the configuration of an organic light-emitting device according to an embodiment of the present invention.

[0033]

Description of Symbols

[0034] 100: Substrate

[0035] 200: Hole injection layer

[0036] 300: Hole transport layer

[0037] 400: Light-emitting layer

[0038] 500: Electron transport layer

[0039] 600: Electron injection layer

[0040] 1000: First electrode

[0041] 2000: Second electrode

[0042] 3000: Cover layer DETAILED DESCRIPTION OF THE EMBODIMENTS

[0043] Before describing the present invention in detail, it should be understood that the terms used in this specification are only for describing specific embodiments and are not intended to limit the scope of the present invention. The scope of the present invention should only be defined by the scope of the appended claims. Unless otherwise clearly stated, all technical terms and scientific terms used in this specification have the same meaning as commonly understood by those of ordinary skill in the art.

[0044] Throughout this specification and the claims, unless otherwise clearly stated, the term "comprise (comprise, comprises, comprising)" only indicates the inclusion of the mentioned elements, steps, or a series of elements and steps, and does not pre-exclude any other element, step, or a series of elements or a series of steps.

[0045] Throughout this specification and the claims, the term "aryl" refers to an arene ring group having 5 to 50 carbon atoms such as phenyl, benzyl, naphthyl, biphenyl, terphenyl, fluorenyl, phenanthryl, triphenylene, phenylene, anthryl, fluoranthenyl, benzofluorenyl, benzotriphenylene, benzo anthryl, stilbenyl, pyrenyl, etc., and "heteroaryl" refers to, for example, pyrrolyl, pyrazinyl, pyridyl, indolyl, isoindolyl, furyl, benzofuryl, isobenzofuryl, dibenzofuryl, benzothienyl, dibenzothienyl, quinolinyl, isoquinolinyl, quinoxalinyl, carbazolyl, phenanthridinyl, acridinyl, phenanthrolinyl, thienyl, and a heterocyclic group composed of a pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, indole ring, quinoline ring, acridine ring, pyrrolidine ring, di alkyl ring, piperidine ring, morpholine ring, piperazine ring, carbazole ring, furan ring, thiophene ring, oxazole ring, diazole ring, benzo oxazole ring, thiazole ring, thiadiazole ring, benzothiazole ring, benzotriazole ring, imidazole ring, benzimidazole ring, pyran ring, dibenzofuran ring, etc., which is an aromatic ring having 3 to 50 carbon atoms containing at least one hetero element.

[0046] Throughout this specification and the claims, the term "substituted or unsubstituted" means substituted or unsubstituted with one or more groups selected from the group consisting of deuterium, halogen, amino, nitro, nitrile, or C1-C30 alkyl, C2-C30 alkenyl, C1-C30 alkoxy, C3-C20 cycloalkyl, C3-C20 heteroalkyl, C6-C30 aryl, and C3-C30 heteroaryl. In addition, throughout this specification of the present application, unless otherwise clearly stated, the same symbols have the same meanings.

[0047] In addition, unless otherwise clearly stated to the contrary, multiple embodiments of the present invention can be combined with certain other embodiments. Next, the embodiments of the present invention and their effects will be described.

[0048] An organic light-emitting device according to an embodiment of the present invention includes: at least one or more organic layers formed between a first electrode and a second electrode; and a covering layer formed on at least one side surface of the first electrode and the second electrode opposite to the organic layer; wherein the covering layer of the present invention may include a compound having a refractive index of 2.26 or more at 450 nm and an attenuation coefficient value at 430 nm in the range of greater than 0.10 and less than 0.17.

[0049] The above-mentioned coating layer can reduce total internal reflection and improve luminous efficiency. Moreover, in order to extend the service life of the device, it can be manufactured using a compound having a refractive index of 2.26 or more at 450 nm and an attenuation coefficient value at 430 nm in the range greater than 0.10 and less than 0.17. Specifically, the refractive index of the above-mentioned compound at 450 nm can be 2.28 or more, and the attenuation coefficient value at 430 nm can be in the range greater than 0.10 and less than 0.15.

[0050] More specifically, the refractive index of the above-mentioned compound at 450 nm can be 2.30 or more, and the attenuation coefficient value at 430 nm can be in the range greater than 0.10 and less than 0.13.

[0051] When the refractive index at 450 nm is above the above range, the light extraction effect can be improved and high efficiency can be achieved thereby. Moreover, by making the attenuation coefficient at 430 nm exceed 0.10, the absorption wavelength in the ultraviolet region can be expanded and the life improvement effect when exposed to external ultraviolet rays can be achieved. In addition, by using a compound having an attenuation coefficient at 430 nm less than 0.17 as the material of the coating layer, the absorption wavelength in the blue visible light region can be minimized and high color purity can be achieved thereby.

[0052] Moreover, the attenuation coefficient value of the above-mentioned compound at 450 nm can be less than 0.01. By satisfying the above range, the absorption wavelength in the blue visible light region can be minimized and higher color purity can be achieved thereby.

[0053] Moreover, the attenuation coefficient value of the above-mentioned compound at 380 nm can be greater than 0.5. By satisfying the above range, the absorption intensity in the ultraviolet region can be improved and a more stable element when exposed to external ultraviolet rays can be achieved thereby.

[0054] In addition, the present invention provides a compound having a tertiary amine structure as a compound for a coating layer applicable to the above-mentioned coating layer. By using the above-mentioned compound for a coating layer, a lower deposition temperature can be maintained and a higher glass transition temperature (Tg) can be formed, thereby improving the thermal stability of the compound during the deposition process.

[0055] As a specific example, it includes a compound for a coating layer represented by Chemical Formula 1 below.

[0056] <Chemical Formula 1>

[0057]

[0058] Among them, A, B, and C are each independently a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 50 carbon atoms.

[0059] Any one or more of A, B, and C is represented by the following Chemical Formula 1-1 or Chemical Formula 1-2:

[0060] Each of L1 to L3 is independently a direct bond, a substituted or unsubstituted C6-C50 arylene group, or a substituted or unsubstituted C2-C50 heteroarylene group.

[0061] <Chemical Formula 1-1>

[0062]

[0063] <Chemical Formula 1-2>

[0064]

[0065] Wherein, each X is independently C, CR, N, O, S, NR or CRR';

[0066] Each of R and R' is independently hydrogen, deuterium, halogen, nitro, nitrile, a substituted or unsubstituted C1-C30 alkyl group, a substituted or unsubstituted C2-C30 alkenyl group, a substituted or unsubstituted C1-C30 alkoxy group, a substituted or unsubstituted C1-C30 mercapto group, a substituted or unsubstituted C6-C50 aryl group, or a substituted or unsubstituted C2-C50 heteroaryl group.

[0067] As a specific example, two or more of A, B, and C in the above Chemical Formula 1 can be represented by the above Chemical Formula 1-1 or Chemical Formula 1-2. In the above-described case, it is possible to achieve the effect of having a high refractive index of 2.26 or more at 450 nm and an attenuation coefficient greater than 0.10 at 430 nm.

[0068] As a specific example, any one or more of A, B, and C in the above Chemical Formula 1 can be represented by the above Chemical Formula 1-1. In the above-described case, it is possible to achieve the effect of having a high refractive index of 2.26 or more at 450 nm and an attenuation coefficient less than 0.17 at 430 nm.

[0069] As a specific example, the above Chemical Formula 1-1 can be a substituted or unsubstituted naphthyl group. By including one or more naphthyl groups in the compound of the present invention, it is possible to achieve the effect of maintaining a high refractive index of 2.26 or more at 450 nm and an attenuation coefficient less than 0.13 at 430 nm.

[0070] As a specific example compound, it includes a compound for a cover layer as described below.

[0071]

[0072] Next, an organic light-emitting device according to an embodiment of the present invention will be described in detail.

[0073] According to an implementation example of the present invention, an organic light-emitting device may include: a first electrode and a second electrode; an organic layer disposed between the inner sides of the first electrode and the second electrode; and a cover layer disposed outside one or more of the first electrode and the second electrode and containing a compound for the cover layer of the present invention.

[0074] Herein, one side of the two side surfaces of the first electrode or the second electrode that is adjacent to the organic layer between the first electrode and the second electrode is referred to as the inner side, and the side that is not adjacent to the organic layer is referred to as the outer side. That is, when the cover layer is disposed outside the first electrode, the first electrode will be between the cover layer and the organic layer, and when the cover layer is disposed outside the second electrode, the second electrode will be between the cover layer and the organic layer.

[0075] According to an implementation example of the present invention, a plurality of organic layers may be interposed between the inner sides of the first electrode and the second electrode of the organic light-emitting device, and a cover layer may be formed outside one or more of the first electrode and the second electrode. The cover layer may be formed simultaneously outside the first electrode and outside the second electrode, or may be disposed only outside the first electrode or outside the second electrode. The cover may include a compound for the cover layer according to the present invention.

[0076] According to an implementation example of the present invention, the cover layer may include alone a compound for the cover layer according to an implementation example of the present invention, or may include two or more kinds or known compounds at the same time.

[0077] An organic light-emitting device according to an implementation example of the present invention may include one or more organic layers between the first electrode and the second electrode, that is, between the inner sides of the first electrode and the second electrode, and a cover layer may be formed outside the first electrode and the second electrode. The organic layer may be a hole transport layer, a light-emitting layer, and an electron transport layer that generally constitute a light-emitting portion, but is not limited thereto.

[0078] The above organic light-emitting device may include one or more organic layers that constitute a light-emitting portion such as a hole injection layer (HIL), a hole transport layer (HTL), a light-emitting layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL) between the first electrode (anode) and the second electrode (cathode).

[0079] For example, the above organic light-emitting device may be as follows Figure 1The structure shown is fabricated. The organic light-emitting element can be formed by laminating, in order from the bottom, a first electrode 1000, a covering layer 3000, a hole injection layer 200, a hole transport layer 300, a light-emitting layer 400, an electron transport layer 500, an electron injection layer 600, a second electrode 2000, and a covering layer 3000.

[0080] Figure 1 In this case, the substrate 100 can be a substrate used in an organic light-emitting element. In particular, a transparent glass substrate or a flexible plastic substrate with excellent mechanical strength, thermal stability, transparency, surface smoothness, processability, and waterproofness can be used.

[0081] The hole injection electrode 1000 is used as an anode for injecting holes into the organic light-emitting element. A material with as low a work function as possible is used to achieve hole injection, and transparent materials such as indium tin oxide (ITO), indium zinc oxide (IZO), and graphene can be used to form it.

[0082] On top of the above anode electrode, the hole injection layer 200 can be formed by depositing a hole injection layer material using methods such as vacuum deposition, spin coating, casting, and the Langmuir-Blodgett (LB) method. When the hole injection layer is formed by vacuum deposition, the deposition conditions will vary depending on the compound used as the material for the hole injection layer 200, the required structure of the hole injection layer, and its thermal properties. Generally, a deposition temperature in the range of 50 - 500 °C, a -8 vacuum degree of 10 -3 to 10 torr, a deposition rate of 0.01 to / s, and a layer thickness in the range of

[0083] to 5 μm can be appropriately selected. In addition, a charge generation layer can be additionally deposited on the surface of the hole injection layer as needed. As the charge generation layer material, general materials can be used, for example, hexacyano-hexaazatriphenylene (HATCN) can be used.

[0084] The above hole transport layer 300 can be formed using well-known compounds. According to an implementation example of the present invention, the hole transport layer 300 can be one or more layers, and a light-emitting auxiliary layer can be formed on the hole transport layer 300.

[0085] On the above hole transport layer 300 or light-emitting auxiliary layer, the light-emitting layer 400 can be formed by depositing a light-emitting layer material using methods such as vacuum deposition method, spin coating method, casting method, Langmuir-Blodgett (LB) method, etc. When forming the light-emitting layer by the above vacuum deposition method, the deposition conditions will vary depending on the compound used, but generally it is advisable to select within a range of conditions almost the same as those for forming the hole injection layer. In addition, as the above light-emitting layer material, well-known compounds can be used as the main agent or dopant.

[0086] In addition, when a phosphorescent dopant is used in the light-emitting layer at the same time, in order to prevent the phenomenon of triplet excitons or holes diffusing into the electron transport layer, a hole blocking material (HBL) can be additionally laminated by vacuum deposition method or spin coating method. The hole blocking material used at this time is not particularly limited, and any well-known substance used as a hole blocking material can be selected. For example, diazole derivatives or benzotriazole derivatives, phenanthroline derivatives or the hole blocking materials described in Japanese Patent Laid-Open No. 11-329734 (A1), etc. The most representative ones include Balq (bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum), phenanthrolines compounds (for example: BCP (bathocuproine) of UDC Corporation), etc.

[0087] An electron transport layer 500 will be formed on the upper part of the light-emitting layer 400 formed in the above-described manner. At this time, the above electron transport layer can be formed by methods such as vacuum deposition method, spin coating method, casting method, etc. In addition, the deposition conditions of the above electron transport layer will vary depending on the compound used, but generally it is advisable to select within a range of conditions almost the same as those for forming the hole injection layer.

[0088] Next, an electron injection layer 600 can be formed by depositing an electron injection layer material on the upper part of the above electron transport layer 500. At this time, the above electron transport layer can be formed by methods such as vacuum deposition method, spin coating method, casting method, etc. using a general electron injection layer material.

[0089] The hole injection layer 200, hole transport layer 300, light-emitting layer 400, and electron transport layer 500 of the above organic light-emitting element can use the substances described below, but are not limited thereto.

[0090]

[0091] Above the electron injection layer 600, the cathode 2000 can be formed by methods such as vacuum deposition or spin coating. As the cathode, various metals can be used. As specific examples, substances such as aluminum, gold, silver, and magnesium are included.

[0092] The organic light-emitting device of the present invention can use not only an organic light-emitting device composed of an anode, a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, an electron injection layer, and a cathode, but also organic light-emitting devices with various structures, and one or two intermediate layers can be additionally formed as needed.

[0093] The thickness of each organic layer formed by the present invention as described above can be adjusted according to the required degree, specifically, it can be 10 to 1000 nm, and more specifically, it can be 20 to 150 nm.

[0094] According to an embodiment of the present invention, a cover layer 3000 can be formed outside the electrode of the anode 1000 with the hole injection layer 200 interposed therebetween. In addition, a cover layer 3000 can be formed outside the electrode of the cathode 3000 with the electron injection layer 600 interposed therebetween. However, it is not limited thereto. The cover layer 3000 can be formed by a deposition process, and the thickness of the cover layer 3000 can be 100 to More specifically, it can be 300 to In the above-described case, problems such as a decrease in the transmittance of the cover layer can be prevented.

[0095] In addition, although not shown, according to an embodiment of the present invention, an organic layer for performing various functions can be additionally formed outside the first electrode and the second electrode with the cover layer interposed therebetween. A cover layer can be directly formed on the outer surface of the first electrode (or the second electrode), and an organic layer can be additionally formed on the cover layer. In addition, an organic layer for performing various functions can be formed on the outer surface of the first electrode (or the second electrode), and a cover layer containing the compound of the present invention can be formed on the organic layer.

[0096] Next, an organic light-emitting device including a cover layer according to an embodiment of the present invention will be described in detail with reference to embodiments. The following embodiments are only for illustrating the present invention, and the scope of the present invention is not limited to the following embodiments.

[0097] <Production Example 1> Synthesis of Compound 1

[0098]

[0099] Using a round-bottom flask, 3.0 g of 2-bromo-6-phenylnaphthalene, 3.1 g of 4'-(naphthalen-2-yl)-[1,1'-biphenyl]-4-amine, 1.5 g of t-BuONa, 0.4 g of Pd2(dba)3, and 0.4 ml of (t-Bu)3P were dissolved in 100 ml of toluene, and then refluxed with stirring. The reaction was confirmed by thin-layer chromatography (TLC), and the reaction was terminated after adding water. The organic layer was extracted with MC, filtered under reduced pressure, and recrystallized to obtain 4.8 g of Compound 1 (yield: 65%).

[0100] m / z: 699.29 (100.0%), 700.30 (58.8%), 701.30 (17.0%), 702.30 (3.2%)

[0101] <Production Example 2> Synthesis of Compound 2

[0102]

[0103] Compound 2 (yield: 63%) was synthesized in the same manner as in Production Example 1, using 6-bromo-2,2'-binaphthalene and 4'-(naphthalen-2-yl)-N-(4-(naphthalen-2-yl)phenyl)-[1,1'-biphenyl]-4-amine in place of 2-bromo-6-phenylnaphthalene and 4'-(naphthalen-2-yl)-[1,1'-biphenyl]-4-amine.

[0104] m / z: 749.31 (100.0%), 750.31 (63.5%), 751.31 (19.6%), 752.32 (4.0%)

[0105] <Production Example 3> Synthesis of Compound 3

[0106]

[0107] Manufacture was carried out in the same manner as in Production Example 1, wherein 6-(4-bromophenyl)-2,2'-binaphthalene and bis(4-(naphthalen-2-yl)phenyl)amine were used to replace 2-bromo-6-phenylnaphthalene and 4'-(naphthalen-2-yl)-[1,1'-biphenyl]-4-amine to synthesize Compound 3 (yield: 61%).

[0108] m / z: 749.31 (100.0%), 750.31 (63.5%), 751.31 (19.6%), 752.32 (4.0%)

[0109] <Production Example 4> Synthesis of Compound 4

[0110]

[0111] Manufacture was carried out in the same manner as in Production Example 1, wherein 2-(4'-bromo-[1,1'-biphenyl]-4-yl)naphthalene and 4'-amino-[1,1'-biphenyl]-4-carbonitrile were used to replace 2-bromo-6-phenylnaphthalene and 4'-(naphthalen-2-yl)-[1,1'-biphenyl]-4-amine to synthesize Compound 4 (yield: 58%).

[0112] m / z: 750.30 (100.0%), 751.31 (62.1%), 752.31 (18.9%), 753.31 (3.8%)

[0113] Manufacture of Organic Light-Emitting Element

[0114] According to Figure 1An organic light-emitting element is fabricated using the structure described in [reference], but some layers are omitted in the manner described below, and only a cover layer is formed on the upper part. The organic light-emitting element is fabricated by laminating, in order from the bottom, a first electrode 1000, a hole injection layer 200, a hole transport layer 300, a light-emitting layer 400, a second electrode 2000, and a cover layer 3000. The following substances shown in Table 1 below are used in the hole injection layer 200, the hole transport layer 300, the light-emitting layer 400, and the electron transport layer 500.

[0115]

Table 1

[0116]

[0117] Example 1.

[0118] On an indium tin oxide (ITO) substrate on which a reflective layer containing Ag is formed, a hole injection layer HI01 HATCN a hole transport layer HT01 is formed by film deposition. Then, as the above-mentioned light-emitting layer, BH01:BD01 3% is doped and is formed by film deposition. Next, as the electron transport layer, ET01:Liq (1:1) is formed by film deposition, and then LiF is deposited to form an electron injection layer. Next, MgAg is deposited with a thickness of 15 nm, and then, as a cover layer above the above-mentioned cathode, the compound fabricated in Production Example 1 is deposited with a thickness. An organic light-emitting element is fabricated by encapsulating the above-mentioned element in a glove box.

[0119] Examples 2 to 4.

[0120] Fabrication is carried out in the same manner as in Example 1 above, and organic light-emitting elements are fabricated respectively after forming the cover layer using the compounds fabricated in Production Examples 2 to 4 by film deposition.

[0121] Comparative Examples 1 to 4.

[0122] Fabrication is carried out in the same manner as in Example 1 above, and organic light-emitting elements are fabricated respectively after forming the cover layer using the compounds of Comparative Examples 1 (Ref.1) to Comparative Examples 4 (Ref.4) represented by the following chemical formulas by film deposition.

[0123]

[0124]

[0125] <Evaluation of Refractive Index and Attenuation Coefficient>

[0126] Using Compounds 1 to 4 and Compounds of Comparative Examples 1 to 4 produced in the above process respectively, a deposited film with a thickness of 30 nm was fabricated on a silicon substrate using a vacuum deposition apparatus, and then the refractive index at 450 nm and the attenuation coefficient at 430 nm were measured using an ellipsometer (J.A. Woollam Co., Inc., M-2000X). The results are shown in Table 2 below.

[0127]

Table 2

[0128]

[0129] As recorded in Table 2 above, it can be confirmed that the refractive indices of Compounds 1 to 4 of the present invention at 450 nm are 2.26 or more, specifically showing a high refractive index of 2.3 or more, and the attenuation coefficients at 430 nm are in the range of greater than 0.1 and less than 0.17, specifically in the range of greater than 0.1 and less than 0.15, and more specifically in the range of greater than 0.1 and less than 0.13.

[0130] <Performance Evaluation of Organic Light-Emitting Devices>

[0131] Electrons and holes were injected by applying a voltage to a Keithley 2400 source measurement unit, and the luminance when emitting light was measured using a Konica Minolta spectroradiometer (CS-2000). Thus, the performance of the organic light-emitting devices of Examples 1 to 4 and Comparative Examples 1 to 4 fabricated through the above process, namely the current density and luminance with respect to the applied voltage, were evaluated under atmospheric pressure conditions. The results are shown in Table 3.

[0132]

Table 3

[0133] Op.V <![CDATA[mA / cm 2 > Cd / A CIEx CIEy LT97 Example 1 3.50 10 7.58 0.143 0.044 175 Example 2 3.50 10 7.60 0.143 0.044 173 Example 3 3.50 10 7.53 0.143 0.043 175 Example 4 3.50 10 7.51 0.143 0.044 170 Comparative Example 1 3.52 10 6.40 0.138 0.054 78 Comparative Example 2 3.57 10 4.55 0.130 0.070 110 Comparative Example 3 3.51 10 6.52 0.138 0.053 135 Comparative Example 4 3.51 10 6.93 0.139 0.050 140

[0134] As shown in Table 3, the refractive index at 450 nm is 2.26 or more, and the attenuation coefficient at 430 nm is in the range of greater than 0.1 and less than 0.17. Moreover, compared with the comparative examples, the driving voltage of the examples of the present invention is lower, the efficiency is higher, and the color purity and service life are improved.

Claims

1. A compound for a cover layer, characterized in that: It is a compound for a cover layer of an organic light-emitting element, which is represented by the following Chemical Formula 1, <Chemical Formula 1> In the above Chemical Formula 1, A, B, and C are each independently a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 50 carbon atoms, and any one or more of A, B, and C are represented by the following Chemical Formula 1-1, L1 to L3 are each independently a direct bond, a substituted or unsubstituted arylene group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroarylene group having 2 to 50 carbon atoms, <Chemical Formula 1-1> In the above Chemical Formula 1-1, Xs are each independently C, CR, N, O, S, NR, or CRR', where R and R' are each independently hydrogen, deuterium, a halogen, a nitro group, a nitrile group, a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, a substituted or unsubstituted alkenyl group having 2 to 30 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 30 carbon atoms, a substituted or unsubstituted mercapto group having 1 to 30 carbon atoms, a substituted or unsubstituted aryl group having 6 to 50 carbon atoms, or a substituted or unsubstituted heteroaryl group having 2 to 50 carbon atoms.

2. The compound for a cover layer according to claim 1, characterized in that: Two or more of A, B, and C in the above Chemical Formula 1 are the above Chemical Formula 1-1.

3. The compound for a cover layer according to claim 1, characterized in that: The above Chemical Formula 1-1 is a substituted or unsubstituted naphthyl group.

4. The compound for a cover layer according to claim 1, characterized in that: The above compound for a cover layer is any one of the following compounds, 5. The compound for a cover layer according to claim 1, characterized in that: The refractive index at 450 nm is 2.26 or more and the attenuation coefficient value at 430 nm is in the range greater than 0.10 and less than 0.

17.

6. The compound for a cover layer according to claim 1, characterized in that: The refractive index at 450 nm is 2.28 or more and the attenuation coefficient value at 430 nm is in the range greater than 0.10 and less than 0.

15.

7. The compound for a cover layer according to claim 1, characterized in that: The refractive index at 450 nm is 2.30 or more and the attenuation coefficient value at 430 nm is in the range greater than 0.10 and less than 0.

13.

8. The compound for a cover layer according to claim 5, characterized in that: The attenuation coefficient value at 450 nm is less than 0.

01.

9. The compound for a cover layer according to claim 5, characterized in that: The attenuation coefficient value at 380 nm is greater than 0.

5.

10. An organic light-emitting element, characterized in that: It is an organic light-emitting element including a cover layer, and the above cover layer contains the compound for a cover layer according to claim 5.

11. The organic light-emitting element according to claim 10, characterized in that: The above organic light-emitting element includes a first electrode and a second electrode, and includes one or more blue light-emitting layers between the above first electrode and the above second electrode.

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