Novel compound for covering layer and organic light-emitting element comprising the same

Abstract

The present invention provides a compound represented by the following chemical formula 1 and an organic light-emitting element comprising the compound:

Description

Technical Field

[0001] The present invention relates to a novel compound for a covering layer and an organic light-emitting element comprising the compound for a covering layer. Background Art

[0002] Materials used as organic layers in organic light-emitting devices can be broadly classified into light-emitting materials, hole-injecting materials, hole-transporting materials, electron-transporting materials, and electron-injecting materials according to their functions.

[0003] In addition, the luminescent materials can be divided into fluorescent materials originating from the singlet excited state of electrons and phosphorescent materials originating from the triplet excited state of electrons according to the luminescence mechanism, and can also be divided into blue, green, and red luminescent materials according to the luminescent color.

[0004] A typical organic light-emitting element has an anode formed on a substrate, and a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode formed on the anode in sequence. The hole transport layer, the light-emitting layer, and the electron transport layer are organic thin films composed of organic compounds.

[0005] The driving principle of the organic light emitting element having the above structure is as follows.

[0006] When a voltage is applied between the anode and cathode, holes injected from the anode move to the light-emitting layer via the hole transport layer, while electrons injected from the cathode move to the light-emitting layer via the electron transport layer. The holes and electrons recombine in the light-emitting layer to generate excitons.

[0007] When these excitons convert from an excited state to a ground state, light is generated. The efficiency of an organic light-emitting device can generally be divided into internal luminous efficiency and external luminous efficiency. Internal luminous efficiency is related to the efficiency of exciton generation and light conversion in organic layers between the first and second electrodes, such as the hole transport layer, the light-emitting layer, and the electron transport layer. Theoretically, the internal luminous efficiency for fluorescence is 25%, while for phosphorescence it is 100%.

[0008] External luminous efficiency refers to the efficiency with which light generated in the organic layer is extracted from the outside of the organic light-emitting element. It is currently known that approximately 20% of the internal luminous efficiency can be extracted externally. To improve this light extraction efficiency, various organic compounds with a refractive index of 1.7 or higher are commonly used as a cover layer to prevent light from being lost due to total internal reflection. Furthermore, efforts have been underway to develop organic compounds with a high refractive index and film stability that can enhance external luminous efficiency in order to improve the performance of organic light-emitting elements. Summary of the Invention

[0009] To this end, the object of the present invention is to provide an organic light-emitting element that can ensure a wider band gap in the visible light region that is difficult to absorb and maintain a high refractive index while increasing the absorption wavelength in the ultraviolet region, thereby achieving high color purity, high efficiency and long service life.

[0010] In addition, the purpose of the present invention is to provide an organic light-emitting element that can improve the film arrangement between molecules by increasing the polarizability of the molecules and thereby improve the refractive index, and can also improve the stability to external air and / or moisture, and can prevent recrystallization between molecules through a higher glass transition temperature (Tg) and decomposition temperature (Td) and maintain the stability of the film when heat is generated during the element driving process, thereby further improving the external quantum efficiency and service life.

[0011] Next, the above-mentioned issues and additional issues will be described in detail.

[0012] As a means of solving the above-mentioned problems,

[0013] One embodiment of the present invention provides a compound for a covering layer represented by the following chemical formula 1:

[0014] <Chemical Formula 1>

[0015]

[0016] In the chemical formula 1,

[0017] X1 to X5 are each independently O, S, C, CR, N, Se, Te, NR, CRR', SiRR' or GeRR', and two or more of them are each O, S, N, Se, Te, NR, CRR', SiRR' or GeRR';

[0018] Ar1 to Ar4 are each independently a substituted or unsubstituted C6-C50 aryl group, or a substituted or unsubstituted C2-C50 heteroaryl group;

[0019] R and R' are each independently hydrogen, deuterium, halogen, nitro, nitrile, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 mercapto, substituted or unsubstituted C3-C30 silyl, substituted or unsubstituted C6-C50 aryl, or substituted or unsubstituted C2-C50 heteroaryl, and R and R' may or may not form a ring by combining with each other.

[0020] L1 and L2 are each independently a direct bond, a substituted or unsubstituted C6-C50 arylene group, or a substituted or unsubstituted C2-C50 heteroarylene group.

[0021] In addition, as one embodiment of the present invention,

[0022] Provided is an organic light-emitting element containing the compound for a covering layer.

[0023] The covering layer compound according to the present invention is a compound comprising, as a core, two amine groups bonded to each other via a linker comprising a specific five-membered ring, and can achieve high color purity by maintaining a wide band gap in the visible light region where absorption is difficult.

[0024] In addition, the compound for the covering layer according to the present invention can be expanded by substituents such as aromatic or heteroaromatic groups bonded to specific 5-membered rings and amino groups, thereby increasing the absorption wavelength in the ultraviolet region while maintaining a high refractive index. Therefore, the external quantum efficiency of the organic light-emitting element can be improved, and the effect of improving the stability to ultraviolet rays is very excellent.

[0025] In particular, since it contains a specific 5-membered ring with minimized volume characteristics and is expanded by adding substituents such as aryl or heteroaryl groups bonded to the amino group, an excellent intermolecular thin film arrangement is ensured, thereby achieving a refractive index improvement effect and significantly improving stability to external air and / or moisture.

[0026] Furthermore, since the cover layer compound according to the present invention has a high glass transition temperature (Tg) and a high decomposition temperature (Td), it is possible to prevent recrystallization between molecules and maintain a stable state of the film when heat is generated during device driving.

[0027] Next, the above-mentioned effects and additional effects will be described in detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic cross-sectional view illustrating the structure of an organic light-emitting element according to an embodiment of the present invention.

[0029] Figure 2 This is a graph showing the absorption intensities of Compounds 6 and 8 for a covering layer according to an embodiment of the present invention and Comparative Compounds 1 and 2 measured in the range of 340 nm to 460 nm.

[0030]

Explanation of symbols

[0031] 100: Substrate

[0032] 200: Hole injection layer

[0033] 300: Hole transport layer

[0034] 400: Luminous layer

[0035] 500: electron transport layer

[0036] 600: electron injection layer

[0037] 1000: 1st electrode (anode)

[0038] 2000: Second electrode (cathode)

[0039] 3000: Overlay DETAILED DESCRIPTION

[0040] Before describing the present invention in detail, it should be understood that the terms used in this specification are intended only to describe specific embodiments and are not intended to limit the scope of the present invention, which is to be determined solely by the appended claims. Unless otherwise expressly stated, all technical and scientific terms used in this specification have the same meanings as those commonly understood by persons of ordinary skill in the art.

[0041] Throughout this specification and claims, unless expressly stated otherwise, terms such as comprise, comprise, or comprising merely indicate the inclusion of the stated item, step, or series of items and steps, and do not preclude any other item, step, or series of items or steps.

[0042] Throughout the specification and claims, the term "aryl" may refer to groups such as phenyl, benzyl, naphthyl, biphenyl, terphenyl, fluorenyl, phenanthrenyl, triphenylene, phenylene, Benzotriphenylene, benzophenone, fluoranthene, benzofluorenyl, benzotriphenylene, benzo The term "heteroaryl" refers to a C5-50 aromatic hydrocarbon ring containing an aromatic ring such as pyrrolyl, pyrazinyl, pyridyl, indolyl, isoindolyl, furyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, quinolyl, isoquinolyl, quinoxalinyl, carbazolyl, phenanthridinyl, acridinyl, phenanthrolinyl, thienyl, and a pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, indole ring, quinoline ring, acridinium ring, pyrrolidine ring, dibenzothiophenyl ring, Alkane ring, piperidine ring, morpholine ring, piperazine ring, carbazole ring, furan ring, thiophene ring, Azole ring, The heterocyclic group is a C2-50 aromatic ring containing one or more hetero elements, such as a diazole ring, a benzofuran ring, a thiazole ring, a thiadiazole ring, a benzothiophene ring, a triazole ring, an imidazole ring, a benzimidazole ring, a pyran ring, or a dibenzofuran ring.

[0043] In addition, Ar in the chemical formula x(wherein x is an integer) unless otherwise specifically defined, represents a substituted or unsubstituted C6-C50 aryl group, or a substituted or unsubstituted C2-C50 heteroaryl group, L x (wherein x is an integer) unless otherwise specifically defined, represents a directly bonded, substituted or unsubstituted C6-C50 arylene group, or a substituted or unsubstituted C2-C50 heteroarylene group, R x (wherein x is an integer) unless explicitly defined otherwise, represents hydrogen, deuterium, halogen, nitro, nitrile, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 mercapto, substituted or unsubstituted C6-C50 aryl, or substituted or unsubstituted C2-C50 heteroaryl.

[0044] Throughout the present specification and claims, the term "substituted or unsubstituted" refers to a group substituted with deuterium, halogen, amino, cyano, nitrile, nitro, nitroso, sulfamoyl, isothiocyanate, thiocyanate, carboxyl, or C1-C30 alkyl, C1-C30 alkylsulfinyl, C1-C30 alkylsulfonyl, C1-C30 alkylsulfanyl, C1-C12 fluoroalkyl, C2-C30 alkenyl, C1-C30 alkoxy, C1-C12 N The present invention may be substituted or unsubstituted with one or more groups selected from the group consisting of an alkylamino group, a C2-C20 N,N-dialkylamino group, a substituted or unsubstituted C1-C30 mercapto group, a C1-C6 N-alkylsulfamoyl group, a C2-C12 N,N-dialkylsulfamoyl group, a C3-C30 silyl group, a C3-C20 cycloalkyl group, a C3-C20 heterocycloalkyl group, a C6-C50 aryl group, and a C2-C50 heteroaryl group, but is not particularly limited thereto. Furthermore, throughout the present specification, unless otherwise expressly stated, the same symbols have the same meanings.

[0045] In addition, unless otherwise explicitly stated to the contrary, the various embodiments of the present invention may be combined with other embodiments. Next, the embodiments of the present invention and their effects will be described.

[0046] Next, the present invention will be described in detail.

[0047] The compound for the covering layer according to the present invention can be represented by the following Chemical Formula 1:

[0048] <Chemical Formula 1>

[0049]

[0050] In the chemical formula 1,

[0051] X1 to X5 are each independently O, S, C, CR, N, Se, Te, NR, CRR', SiRR' or GeRR', and two or more of them are each O, S, N, Se, Te, NR, CRR', SiRR' or GeRR';

[0052] Ar1 to Ar4 are each independently a substituted or unsubstituted C6-C50 aryl group, or a substituted or unsubstituted C2-C50 heteroaryl group;

[0053] R and R' are each independently hydrogen, deuterium, halogen, nitro, nitrile, substituted or unsubstituted C1-C30 alkyl, substituted or unsubstituted C2-C30 alkenyl, substituted or unsubstituted C1-C30 alkoxy, substituted or unsubstituted C1-C30 mercapto, substituted or unsubstituted C3-C30 silyl, substituted or unsubstituted C6-C50 aryl, or substituted or unsubstituted C2-C50 heteroaryl, and R and R' may or may not form a ring by combining with each other.

[0054] L1 and L2 are each independently a direct bond, a substituted or unsubstituted C6-C50 arylene group, or a substituted or unsubstituted C2-C50 heteroarylene group.

[0055] Specifically, in Chemical Formula 1, any one or more of X1 to X5 may be C or N. In the above case, the C or N is bonded to the linker (L1 and / or L2).

[0056] The capping layer compound represented by Chemical Formula 1 is a compound comprising two amine groups as a core structure bonded via a specific five-membered ring containing two or more heteroatoms, or one or more heteroatoms and one or more CRR's. This compound exhibits high color purity by maintaining a band gap that is difficult to absorb in the visible light region. Furthermore, while maintaining a high refractive index, it can increase the absorption wavelength in the ultraviolet region, thereby improving the external quantum efficiency of organic light-emitting devices and enhancing their stability against ultraviolet light.

[0057] Specifically, the chemical formula 1 can be represented by the following chemical formula 2:

[0058] <Chemical Formula 2>

[0059]

[0060] In the chemical formula 2,

[0061] Definitions of X1 to X5 and Ar1 to Ar4 are the same as those in Chemical Formula 1, l and m are each independently an integer of 0 to 3, and l+m is 1 or greater.

[0062] The coating layer compound represented by Chemical Formula 2 has a structure in which the linking groups between the amine group and the specific five-membered ring (L1 and L2 in Chemical Formula 1) are directly bonded or contain one or more phenylene groups, and is characterized in that at least one of L1 and L2 is not directly bonded. The compound of the present invention can significantly increase the refractive index and enhance the absorption strength in the ultraviolet region.

[0063] Specifically, l and m may be integers greater than or equal to 1, and more specifically, may be 1. As described above, by minimizing the linking groups, it is possible to effectively reduce unnecessary light absorption in the long wavelength region while achieving a high refractive index.

[0064] More specifically, the chemical formula 1 can be represented by the following chemical formula 3:

[0065] <Chemical Formula 3>

[0066]

[0067] In the chemical formula 3,

[0068] Definitions of X1 to X5 and Ar1 to Ar4 are the same as those in Chemical Formula 1.

[0069] The compound for the covering layer represented by Chemical Formula 3 is a compound in which the linking group between the amine group and the specific 5-membered ring (L1 and L2 in Chemical Formula 1) is a p-phenylene (1,4-phenylene) group. By minimizing the connection, it can achieve a high refractive index while minimizing unnecessary light absorption in the long wavelength region.

[0070] Furthermore, in any one of the Chemical Formulas 1 to 3,

[0071] Specific 5-membered ring The present invention may include any of the structures A-1 to A-24 below, and more specifically, any of the structures A-1 to A-10. In this case, by minimizing the core volume, absorption in the visible region can be minimized while maintaining a high refractive index, and the deposition temperature can be effectively improved. In particular, when any of the structures A-6 to A-10 is included, the refractive index can be significantly improved.

[0072]

[0073] In the structures A-1 to A-24,

[0074] R1 and R2 are each independently hydrogen, deuterium, a substituted or unsubstituted C1-C10 alkyl group, a substituted or unsubstituted C6-C30 aryl group, or a substituted or unsubstituted C4-C20 heteroaryl group,

[0075] * indicates the position of the amino group bonded to the amino group via the linker L1 and / or L2.

[0076] Specifically, R1 and R2 can each independently be hydrogen, methyl, ethyl, isopropyl, or phenyl. In such cases, the volume characteristics of the specific 5-membered ring can be minimized, thereby further enhancing the refractive index improvement effect.

[0077] In particular, R1 and R2 may be hydrogen, methyl, or phenyl, thereby significantly reducing the volume characteristics of the specific 5-membered ring, thereby greatly enhancing the refractive index improvement effect of the compound.

[0078] In any one of Chemical Formulas 1 to 3, The volume characteristics of the compound can be minimized by adopting a specific five-membered ring structure such as the structures represented by structures A-1 to A-24, and a wide band gap in the visible light region that is difficult to absorb can be maintained by adopting a specific five-membered ring structure containing at least two heteroatoms or at least one heteroatom and one CRR' within the specific five-membered ring, thereby exhibiting high color purity.

[0079] Specifically, because Containing two or more heteroatoms, specifically one or two or more N atoms, can further increase the polarizability of the compound to increase the refractive index, and can also increase the intensity of absorption of light in the ultraviolet region.

[0080] Furthermore, in any one of the Chemical Formulas 1 to 3,

[0081] The Ar1 to Ar4 may each independently include phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, pyridyl, furyl, thienyl, pyrrolyl, quinolyl, benzofuranyl, benzothiophenyl, carbazolyl, benzothiazolyl, benzo oxazolyl, benzimidazolyl, benzotriazolyl, dibenzofuranyl, dibenzothiophenyl or a combination thereof.

[0082] Specifically, Ar1 to Ar4 each independently include any one of the structures represented by the following structures B-1 to B-32, more specifically, include any one of structures B-1 to B-9, B-13, B-14, B-16, B-20 to B-24. In addition, at least one of Ar1 to Ar4 may include any one of B-2 to B-9, B-13, B-14, B-16, B-20 to B-24, specifically, Ar1 and Ar3 may include any one of B-2 to B-9, B-13, B-14, B-16, B-20 to B-24. In the above case, thermal stability can be further improved while having a higher refractive index:

[0083]

[0084]

[0085] In the structures B-1 to B-32,

[0086] R3 and R4 are each independently hydrogen, deuterium, substituted or unsubstituted C1-C10 alkyl, substituted or unsubstituted C6-C30 aryl, or substituted or unsubstituted C4-C20 heteroaryl,

[0087] n is an integer from 0 to 3.

[0088] As an example, R3 and R4 can each independently be hydrogen; or phenyl.

[0089] By adopting the above-mentioned structure in Ar1 to Ar4, the bulk characteristics of the substituent can be minimized, thereby achieving a higher refractive index and efficient light absorption in the ultraviolet region according to the coating layer compound of the present invention, and excellent thin film alignment between molecules.

[0090] Specifically, one or more of Ar1 to Ar4 may contain a heteroaryl group or a condensed aromatic group, or contain an aromatic group with 7 or more carbon atoms, specifically 10 or more carbon atoms. In this case, the refractive index can be further improved, thereby achieving a refractive index of 2.25 or more.

[0091] The following compounds are specific examples of the compounds according to the present invention. The following examples are merely illustrative of the present invention and the present invention is not limited thereto:

[0092]

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103]

[0104]

[0105]

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112]

[0113]

[0114]

[0115]

[0116]

[0117]

[0118]

[0119]

[0120] One embodiment of the compound of the present invention can be synthesized through an amination reaction, and its general synthesis reaction formula is shown below.

[0121]

[0122] In another embodiment of the present invention, an organic light-emitting element is provided, wherein the compound for a covering layer according to the present invention is included in the covering layer.

[0123] Next, the organic light emitting element according to the present invention will be described in more detail.

[0124] In one embodiment of the present invention, the organic light-emitting element may include a first electrode, a second electrode, and one or more organic layers and a covering layer between the first electrode and the second electrode. The covering layer may be arranged on the outside of any one or more electrodes of the first electrode and the second electrode.

[0125] Specifically, of the two side surfaces of the first electrode or the second electrode, the side adjacent to the organic layer interposed between the first and second electrodes is referred to as the inner side, and the side not adjacent to the organic layer is referred to as the outer side. That is, when the covering layer is disposed outside the first electrode, the first electrode is interposed between the covering layer and the organic layer, whereas when the covering layer is disposed outside the second electrode, the second electrode is interposed between the covering layer and the organic layer.

[0126] Furthermore, in one embodiment of the present invention, one or more organic layers may be interposed between the first and second electrodes of the organic light-emitting element, and a covering layer may be formed outside one or more of the first and second electrodes. Specifically, the covering layer may be formed on both the outside of the first and second electrodes, or may be formed only on the outside of the first or second electrode.

[0127] In this case, the covering layer may contain the compound for a covering layer according to the present invention, and may contain the compound for a covering layer according to the present invention alone, or may contain two or more compounds or a combination of known compounds.

[0128] Furthermore, the refractive index of the cover layer at a wavelength of 450 nm may be greater than 2.25, specifically greater than 2.30, and the ultraviolet absorption intensity at a wavelength of 380 nm may be greater than 0.7, specifically greater than 0.8 or greater than 0.9.

[0129] Furthermore, the organic layer may include 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.

[0130] Specifically, an organic light-emitting element according to an embodiment of the present invention may include one or more organic layers constituting 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 a first electrode (anode) and a second electrode (cathode).

[0131] Figure 1 The organic light emitting element according to an embodiment of the present invention is schematically illustrated in a cross-sectional view. Figure 1 The structure shown is manufactured.

[0132] like Figure 1 As shown, the organic light-emitting element can be a structure in which a substrate 100, a first electrode 1000, 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 are stacked in sequence from bottom to top.

[0133] The substrate 100 may be a substrate commonly used in organic light-emitting elements, and in particular, may be a transparent glass substrate or a flexible plastic substrate having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and waterproofness.

[0134] Furthermore, the first electrode 1000 serves as a hole injection electrode for injecting holes into the organic light-emitting element. To facilitate hole injection, the first electrode 1000 is made of a material with the lowest possible work function, such as indium tin oxide (ITO), indium zinc oxide (IZO), or graphene, a transparent material.

[0135] Meanwhile, the hole injection layer 200 can be formed by depositing a hole injection layer material on the upper portion of the first electrode 1000 using methods such as vacuum deposition, spin coating, casting, and Langmuir-Blodgett (LB) methods. When forming the hole injection layer 200 by vacuum deposition, the deposition conditions vary depending on the compound used as the material of the hole injection layer 200, the desired structure of the hole injection layer 200, and the thermal properties. Generally, the deposition temperature can be 50 to 500°C, 10 -8 to 10 -3 Torr vacuum degree, 0.01 to Deposition rate / second and The thickness can be appropriately selected within the range of 1 to 5 μm. In addition, a charge generation layer can be additionally deposited on the surface of the hole injection layer 200 as needed. As the charge generation layer material, a general material can be used, for example, hexacyano-hexaazatriphenylene (HATCN) can be used.

[0136] In addition, the hole transport layer 300 can be formed by depositing a hole transport layer material on the upper part of the hole injection layer 200 using a method such as vacuum deposition, spin coating, casting, Langmuir-Brøgeta (LB) method, etc. When the hole transport layer 300 is formed by the vacuum deposition method, its deposition conditions will vary depending on the compound used, but it is generally appropriate to select conditions within a range that is almost the same as the conditions for forming the hole injection layer 200. The hole transport layer 300 can be formed using well-known compounds. The hole transport layer 300 as described above can be more than one layer, and although in Figure 1 Although not shown in the figure, a luminescence auxiliary layer may be additionally formed on the hole transport layer 300 .

[0137] Meanwhile, the light-emitting layer 400 can be formed by depositing a light-emitting layer material on top of the hole transport layer 300 or the light-emitting auxiliary layer using methods such as vacuum deposition, spin coating, casting, and the Langmuir-Brötten (LB) method. When forming the light-emitting layer 400 by the vacuum deposition method, the deposition conditions will vary depending on the compound used, but are generally preferably selected within a range of conditions that are substantially the same as those used for forming the hole injection layer 200. As the light-emitting layer material, known compounds can be used as a main agent or a dopant.

[0138] When a phosphorescent dopant is used in the light-emitting layer material, in order to prevent triplet excitons or holes from diffusing to the electron transport layer 500, a stacked hole blocking material (HBL) can be added on the upper part of the light-emitting layer 400 by vacuum deposition or spin coating. The hole blocking material that can be used is not particularly limited, and any known material can be used. For example, Examples of hole-blocking materials include oxadiazole derivatives, benzotriazole derivatives, o-phenanthroline derivatives, and those described in Japanese Patent Application Laid-Open No. 11-329734(A1). Representative examples include Balq (bis(8-hydroxy-2-methylquinolinol)-(4-phenylphenoxy)aluminum) and phenanthroline compounds (e.g., BCP (bathocuproine) from UDC). The light-emitting layer 400 of the present invention may include one or more blue light-emitting layers, or two or more blue light-emitting layers.

[0139] Furthermore, the electron transport layer 500 is formed on the upper portion of the light-emitting layer 400 and can be formed by methods such as vacuum deposition, spin coating, and casting. The deposition conditions of the electron transport layer 500 vary depending on the compound used, but are generally preferably selected within a range of conditions that are substantially the same as those used for forming the hole injection layer 200.

[0140] Furthermore, the electron injection layer 600 can be formed by depositing an electron injection layer material on the electron transport layer 500 , and can be formed by methods such as vacuum deposition, spin coating, and casting.

[0141] Meanwhile, the second electrode 2000 serves as an electron injection electrode and can be formed on the electron injection layer 600 by vacuum deposition or spin coating. Various metals can be used as the material for the second electrode 2000. Specific examples include, but are not limited to, aluminum, gold, silver, and magnesium.

[0142] The organic light-emitting element of the present invention can not only use the organic light-emitting element as described above, which includes the covering layer 3000, the first electrode 1000, the hole injection layer 200, the hole transport layer 300, the light-emitting layer 400, the electron transport layer 500, the electron injection layer 600, the second electrode 2000 and the covering layer 3000, but can also use organic light-emitting elements of various structures, and can also add an intermediate layer including one or two layers as needed.

[0143] Furthermore, the thickness of each organic layer formed by the present invention can be adjusted as needed, and specifically can be 10 to 1000 nm, more specifically 20 to 150 nm.

[0144] The covering layer 3000 is as follows Figure 1 As shown, the cover layer 3000 may be formed on the outer side of the first electrode 1000 where the hole injection layer 200 is not formed. In addition, the cover layer 3000 may be formed on the outer side of the second electrode 2000 where the electron injection layer 600 is not formed, but the present invention is not limited thereto. The cover layer 3000 may be formed by a deposition process, and the thickness of the cover layer 3000 may be 100 to 100 μm. More specifically, it can be 300 to By adjusting the thickness as described above, the problem of a decrease in transmittance of the cover layer 3000 can be prevented.

[0145] In addition, although Figure 1Although not shown in the figure, according to an embodiment of the present invention, an organic layer for performing various functions may be additionally formed between the cover layer 3000 and the first electrode 1000 or between the cover layer 3000 and the second electrode 2000. Alternatively, an organic layer for performing various functions may be additionally formed on the upper portion (outer surface) of the cover layer 3000, but the present invention is not limited thereto.

[0146] Next, the present invention will be described in more detail by using a synthesis example of a compound according to an embodiment of the present invention and an example of an organic light-emitting device. The following synthesis example and examples are only used to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

[0147] <Synthesis Example 1> Synthesis of Compound 6

[0148]

[0149] 100 ml of toluene was poured into a round-bottom flask, and 2.0 g of 2,5-bis(4-bromophenyl)-1,3,4- The mixture was stirred under reflux. The reaction progress was confirmed by thin-layer chromatography (TLC), and water was added to terminate the reaction. The organic layer was extracted with dichloromethane (MC), filtered under reduced pressure, and then recrystallized to obtain 2.7 g of compound 6 (yield 64%).

[0150] m / z: 808.32 (100.0%), 809.32 (64.2%), 810.33 (19.6%), 811.33 (4.1%), 810.32 (1.1%)

[0151] <Synthesis Example 2> Synthesis of Compound 8

[0152]

[0153] The same method as in Synthesis Example 1 was followed, except that compound 8 was synthesized using N-([1,1'-biphenyl]-4-yl)naphthalen-2-amine instead of 4-(naphthalen-2-yl)-N-phenylaniline (yield: 61%).

[0154] m / z: 808.32 (100.0%), 809.32 (64.2%), 810.33 (19.6%), 811.33 (4.1%), 810.32 (1.1%)

[0155] <Synthesis Example 3> Synthesis of Compound 9

[0156]

[0157] The same method as in Synthesis Example 1 was followed, except that N-phenyl-[1,1':4',1''-terphenyl]-4-amine was used instead of 4-(naphthalen-2-yl)-N-phenylaniline to synthesize compound 9 (yield 63%).

[0158] m / z: 860.35 (100.0%), 861.35 (68.5%), 862.36 (22.7%), 863.36 (5.4%), 862.35 (1.0%)

[0159] <Synthesis Example 4> Synthesis of Compound 99

[0160]

[0161] The same method as in Synthesis Example 1 was used, wherein 3,5-bis(4-bromophenyl)-1,2,4- oxadiazole (3,5-bis(4-bromophenyl)-1,2,4-oxadiazole) instead of 2,5-bis(4-bromophenyl)-1,3,4- Compound 99 was synthesized from oxadiazole (2,5-bis(4-bromophenyl)-1,3,4-oxadiazole) in a 66% yield.

[0162] m / z: 808.32 (100.0%), 809.32 (64.2%), 810.33 (19.6%), 811.33 (4.1%), 810.32 (1.1%)

[0163] <Synthesis Example 5> Synthesis of Compound 105

[0164]

[0165] The same method as in Synthesis Example 1 was used, wherein 5-(4-bromophenyl)-2-phenyl oxazole (5-(4-bromophenyl)-2-phenyloxazole) instead of 2-(4-bromophenyl)-5-phenyl-1,3,4- Compound 105 was synthesized from oxadiazole (2-(4-bromophenyl)-5-phenyl-1,3,4-oxadiazole) in a 61% yield.

[0166] m / z: 774.30 (100.0%), 775.30 (60.0%), 776.31 (17.0%), 777.31 (3.5%), 776.30 (1.3%)

[0167] <Synthesis Example 6> Synthesis of Compound 1

[0168]

[0169] The same method as in Synthesis Example 1 was used, except that diphenylamine was used instead of 4-(naphthalen-2-yl)-N-phenylaniline to synthesize Compound 1 (yield 50%).

[0170] m / z: 556.2263 (100.0%), 557.2297 (41.1%), 558.2330 (8.2%), 557.2233 (1.5%), 559.2364 (1.1%)

[0171] <Synthesis Example 7> Synthesis of Compound 42

[0172]

[0173] The same method as in Synthesis Example 1 was followed, except that 4-(benzofuran-2-yl)-N-phenylaniline was used instead of 4-(naphthalen-2-yl)-N-phenylaniline to synthesize compound 42 (yield 63%).

[0174] m / z: 788.2787 (100.0%), 789.2821 (58.4%), 790.2855 (16.7%), 791.2888 (3.1%), 789.2758 (1.5%)

[0175] <Synthesis Example 8> Synthesis of Compound 45

[0176]

[0177] The same method as in Synthesis Example 1 was used to prepare the Compound 45 was synthesized in 60% yield by replacing 4-(naphthalen-2-yl)-N-phenylaniline with 4-(benzo[d]oxazol-2-yl)-N-phenylaniline.

[0178] m / z: 790.2692 (100.0%), 791.2726 (56.2%), 792.2759 (15.5%), 793.2793 (2.8%), 791.2663 (2.2%), 792.2696 (1.2%)

[0179] <Synthesis Example 9> Synthesis of Compound 123

[0180]

[0181] The same method as in Synthesis Example 1 was used, wherein 2,5-bis(4-bromophenyl)-1,3,4-thiadiazole and N-phenylbiphenyl-4-amine were used instead of 2,5-bis(4-bromophenyl)-1,3,4-thiadiazole. Compound 123 (yield 58%) was synthesized from oxadiazole (2,5-bis(4-bromophenyl)-1,3,4-oxadiazole) and 4-(naphthalen-2-yl)-N-phenylaniline.

[0182] m / z: 724.2661 (100.0%), 725.2694 (54.1%), 726.2728 (14.3%), 726.2619 (4.5%), 727.2761 (2.5%), 727.2652 (2.4%), 725.2631 (1.5%)

[0183] Manufacturing of organic light-emitting devices

[0184] Figure 1 This is a schematic diagram illustrating the structure of a general organic light-emitting element. As an example of the present invention, Figure 1 In addition to the structure of the illustrated organic light-emitting element, a charge generation layer (not shown) is additionally introduced between the hole injection layer 200 and the hole transport layer 300, and an electron injection layer (not shown) is additionally introduced between the electron transport layer 500 and the cathode 2000. Specifically, the manufactured organic light-emitting element is stacked in the following order from bottom to top: anode (hole injection electrode 1000) / hole injection layer 200 / charge generation layer (not shown) / hole transport layer 300 / light-emitting layer 400 / electron transport layer 500 / electron injection layer 600 / cathode (electron injection electrode 2000) / capping layer 3000.

[0185] When manufacturing an organic light-emitting element, the substrate 10 may be a transparent glass substrate or a flexible plastic substrate.

[0186] The hole injection electrode 1000 is used as an anode for injecting holes into the organic light emitting element. To achieve hole injection, a material with the lowest possible work function is used, such as indium tin oxide (ITO), indium zinc oxide (IZO), or transparent materials such as graphene.

[0187] The materials shown in Table 1 below were used in the hole injection layer 200 , the charge generation layer, the hole transport layer 300 , the light emitting layer 400 , the electron transport layer 500 , and the electron injection layer 600 .

[0188] Furthermore, a cathode 2000 for injecting electrons is formed on the upper side of the electron injection layer 600. Various metals can be used as the cathode, and specific examples include aluminum, gold, and silver.

[0189]

Table 1

[0190]

[0191] <Example 1>

[0192] The indium tin oxide (ITO) substrate with a silver (Ag) reflective layer formed thereon was cleaned using distilled water ultrasonic waves. After the distilled water washing was completed, ultrasonic cleaning was performed using a solvent such as isopropyl alcohol, acetone, and methanol, and then dried. Next, a film was formed on the indium tin oxide (ITO) substrate using a thermal vacuum evaporator as a hole injection layer. HI01 as the charge generation layer HATCN and as a hole transport layer Next, the main body BH01 is doped with a dopant BD01 at 3 wt% to form a film. Next, a film was formed using a mixture of ET01 and Liq (1:1, wt. / wt.). The electron transport layer is then formed by LiF deposition. After the electron injection layer of 100 nm thickness, a cathode of 15 nm thickness was formed by MgAg deposition. The compound prepared in Synthesis Example 1 was coated with 100 Å of 100 Å. The organic light emitting device was manufactured by encapsulating the device in a glove box.

[0193] <Example 2> to <Example 6>

[0194] The same method as in Example 1 was used to manufacture organic light-emitting elements, and the compounds manufactured in Synthesis Examples 2 to 6 were used to deposit and form a capping layer.

[0195] <Comparative Example 1> to <Comparative Example 3>

[0196] The same method as in Example 1 was used to manufacture an organic light-emitting element, wherein a capping layer was formed by depositing comparative compounds 1 to 3 shown in Table 2 below.

[0197]

Table 2

[0198]

[0199] <Test Example 1> Performance Evaluation of Organic Light-Emitting Element

[0200] By applying voltage to a Keithley 2400 source measurement unit to inject electrons and holes, and measuring the brightness of the emitted light using a Konica Minolta spectroradiometer (CS-2000), the performance of the organic light-emitting elements of Examples 6 to 10 and Comparative Examples 1 to 3, namely, the current density and brightness relative to the applied voltage, were evaluated under atmospheric pressure conditions. The results are shown in Table 3.

[0201]

Table 3

[0202] Op.V <![CDATA[mA / cm 2 ]]> Cd / A CIEx CIE LT97 Example 1 3.46 10 7.32 0.141 0.042 153 Example 2 3.46 10 7.36 0.141 0.042 157 Example 3 3.46 10 7.34 0.141 0.042 152 Example 4 3.47 10 7.31 0.140 0.042 155 Example 5 3.47 10 7.26 0.140 0.043 146 Example 6 3.48 10 6.92 0.140 0.046 130 Comparative Example 1 3.50 10 6.03 0.131 0.050 97 Comparative Example 2 3.50 10 5.62 0.131 0.081 81 Comparative Example 3 3.48 10 6.35 0.137 0.052 118

[0203] By comparing with the examples of the present invention, it can be found that the organic light emitting element of the examples can achieve a lower driving voltage, and its luminous efficiency and service life are also significantly improved.

[0204] Specifically, referring to Table 3, the organic light-emitting element of the embodiment uses a compound having a structure containing two amine groups connected by a specific heterocyclic ring to achieve a high molecular polarizability and glass transition temperature (Tg) to form a covering layer. As a result, the refractive index of the covering layer can be increased and the absorption wavelength in the ultraviolet region can be increased, while also forming a stable thin film. In particular, the compound can be formed by containing Azoles, The specific heterocyclic ring such as oxadiazole is contained in the covering layer to minimize the volume characteristics of the molecule. Therefore, the organic light-emitting element of the embodiment in which it is included in the covering layer has higher color purity and is more effective in improving the efficiency and service life of the element than the organic light-emitting elements of Comparative Examples 1 to 3.

[0205] <Test Example 2> Refractive Index Evaluation

[0206] Using Synthesis Example 1 (Compound 6), Synthesis Example 2 (Compound 8), and Synthesis Example 3 (Compound 9) according to the present invention and Comparative Compounds 1 and 3 in Table 2, a 30 nm thick deposited film was produced on a silicon substrate using a vacuum deposition apparatus. The refractive index at a wavelength of 450 nm was then measured using an ellipsometer (JA Woollam Co., Inc., M-2000X). The results are shown in Table 4 below.

[0207]

Table 4

[0208]

[0209] As shown in Table 4, the compounds according to the present invention can be confirmed to have a refractive index of 2.25 or greater, specifically 2.30 or greater, and more specifically 2.35 or greater at a wavelength of 450 nm. As described above, because the compounds according to the present invention exhibit a high refractive index, when used in a cover layer, organic light-emitting devices with significantly improved external quantum efficiency and lifetime can be realized.

[0210] <Test Example 3> Evaluation of UV Absorption Intensity

[0211] Using Synthesis Example 1 (Compound 6) and Synthesis Example 2 (Compound 8) according to the present invention and Comparative Compound 1 and Comparative Compound 2 in Table 2, a 30 nm thick deposited film was prepared on a silicon substrate using a vacuum deposition device, and then the absorption wavelength at a wavelength of 340 nm to 460 nm was measured using an ellipsometer device (JA Woollam Co. Inc, M-2000X). The results are as follows. Figure 2 shown.

[0212] like Figure 2 As shown, the absorption intensity of the compounds according to the present invention at a wavelength of 380 nm in the ultraviolet region was confirmed to be 0.8 or greater, specifically 0.9 or greater, representing an increase of 30% or greater, specifically 50% or greater, compared to Comparative Compounds 1 and 2. Furthermore, it was confirmed that the compounds used in Examples 1 and 2 had no absorption wavelength in the 450 nm region compared to Comparative Compound 2. As described above, the compounds according to the present invention exhibit an effect of increasing absorption wavelength in the ultraviolet region. Therefore, when used as a cover layer, organic light-emitting devices with high color purity, high efficiency, and a long life can be realized.

Claims

1. A covering layer comprising a covering layer compound, wherein the covering layer compound is represented by the following chemical formula 1 or express: Chemical formula 1 In the chemical formula 1, is any one of the structures represented by the following A-1 to A-10, Ar2 to Ar4 are each independently phenyl, biphenyl, terphenyl, naphthyl, fluorenyl, pyridyl, furyl, thienyl, pyrrolyl, quinolyl, benzofuranyl, benzothiophenyl, carbazolyl, benzothiazolyl, benzo oxazolyl, benzimidazolyl, benzotriazolyl, dibenzofuranyl, dibenzothiophenyl and combinations thereof, or any one of the following structures B-6, B-15, B-22, B-24 and B-28 to B-32, L1 and L2 are each independently a direct bond or a C6 arylene group, Ar1 includes any one of the structures represented by B-3, B-4, B-6 to B-32 in the following structures: In the structures B-3, B-4, B-6 to B-32, R3 and R4 are each independently hydrogen, deuterium, C1-C10 alkyl, C6-C30 aryl, or C4-C20 heteroaryl, n is an integer from 0 to 3.

2. The covering layer comprising the covering layer compound according to claim 1, The chemical formula 1 is represented by the following chemical formula 2: Chemical formula 2 In the chemical formula 2, right Ar1 to Ar4 are defined as in Chemical Formula 1, l and m are each independently an integer of 0 or 1, and l+m is 1 or greater.

3. The covering layer comprising the covering layer compound according to claim 1, The chemical formula 1 is represented by the following chemical formula 3: Chemical formula 3 In the chemical formula 3, right The definitions of Ar1 to Ar4 are the same as those in Chemical Formula 1.

4. The covering layer comprising the covering layer compound according to claim 1, The compound of Chemical Formula 1 is any one of the compounds represented by the following chemical formulas: 5 . An organic light-emitting element comprising the covering layer according to claim 1 .

6. The organic light-emitting element according to claim 5, The organic light-emitting element comprises: 1st electrode; a second electrode; and One or more organic layers are located inside the first electrode and the second electrode; The covering layer is arranged outside one or more of the first electrode and the second electrode.

7. The organic light-emitting element according to claim 5, wherein: The cover layer has a refractive index of 2.25 or greater at a wavelength of 450 nm.

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