Novel compound for capping layer, and organic light-emitting device comprising same

Abstract

The present invention provides a novel compound for a capping layer and an organic light-emitting device comprising same.

Description

Novel compound for capping layer and organic light-emitting device comprising same

[0001] The present invention relates to a compound for a capping layer and an organic light-emitting device comprising the same.

[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] And the above luminescent material can be classified into a fluorescent material derived from a singlet excited state of electrons and a phosphorescent material derived from a triplet excited state of electrons according to the luminescent mechanism, and can be classified into blue, green, and red luminescent materials according to the luminescent color.

[0004] A typical organic light-emitting device may have a structure in which an anode is formed on top of a substrate, and a hole transport layer, a light-emitting layer, an electron transport layer, and a cathode are sequentially formed on top of the anode. Here, the hole transport layer, the light-emitting layer, and the electron transport layer are organic thin films made of organic compounds.

[0005] The driving principle of an organic light-emitting device having the structure described above 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, and 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 this exciton changes from the excited state to the ground state, light is generated. The efficiency of organic light-emitting devices can be generally divided into internal luminescence efficiency and external luminescence efficiency. The internal luminescence efficiency is related to how efficiently excitons are generated and light conversion occurs in the organic layer interposed between the first and second electrodes, such as the hole transport layer, the light-emitting layer, and the electron transport layer, and is theoretically known to be 25% for fluorescence and 100% for phosphorescence.

[0008] Meanwhile, the external luminescence efficiency represents the efficiency with which light generated in the organic layer is extracted to the outside of the organic light-emitting device, and it is known that the level of light extracted to the outside is typically about 20% of the internal luminescence efficiency. To increase this light extraction, various organic compounds with a refractive index of 1.7 or higher have been applied as capping layers to prevent the light going out from being lost through total reflection. In addition, efforts have been made to develop organic compounds with high refractive index and thin film stability that increase the external luminescence efficiency to improve the performance of organic light-emitting devices.

[0009] The present invention provides a compound for a capping layer having an arylamine structure having a naphthobenzofuran group with a linker extension on one side and a heteroaryl substituent with a high polarizability on the other side, which has a wide band gap with low light absorption in the visible light region and a high refractive index, while at the same time increasing the absorption wavelength in the ultraviolet region.

[0010] In addition, the purpose is to provide an organic light-emitting device capable of realizing high color purity, high efficiency, and long life by introducing the compound for the capping layer into the capping layer.

[0011] In addition, the purpose is to provide a compound for a capping layer and an organic light-emitting device including the same, which can secure a higher refractive index by improving the intermolecular thin film arrangement through the expansion of the connector.

[0012] In addition, the present invention aims to provide a compound for a capping layer that is more effective in increasing external quantum efficiency and improving lifespan, and an organic light-emitting device including the compound, which not only improves stability from external air and moisture, but also has high Tg and high Td, so as to effectively prevent intermolecular recrystallization and maintain a stable thin film from heat generated during operation of an organic light-emitting device.

[0013] The above tasks and additional tasks are described in detail below.

[0014] In order to solve the above-described problem, the present invention, in one embodiment,

[0015] A compound for a capping layer represented by the following chemical formula 1 is provided:

[0016] <Chemical Formula 1>

[0017]

[0018] <Chemical Formula 1-1>

[0019]

[0020] <Chemical Formula 1-2>

[0021]

[0022] <Chemical Formula 1-3>

[0023]

[0024] <Chemical Formula 1-4>

[0025]

[0026] In the above chemical formula 1 and chemical formula 1-1 to chemical formula 1-4,

[0027] Ar1 is selected from the chemical formulas 1-1 to 1-4,

[0028] X is independently O or S,

[0029] X1 to X8 are each independently C, CR, or N, provided that at least one of X1 to X8 is N,

[0030] Y is O, S, or NR,

[0031] Z1 to Z7 are each independently C, CR, or N,

[0032] Ar2 is a substituted or unsubstituted C2~C50 heteroaryl group,

[0033] Ar is a substituted or unsubstituted C5~C50 arylene group, a substituted or unsubstituted C2~C50 heteroarylene group, or a combination thereof,

[0034] L1 and L2 are each independently a direct bond, a substituted or unsubstituted C5~C50 arylene group, a substituted or unsubstituted C2~C50 heteroarylene group, or a combination thereof,

[0035] R, R1 and R2 are each independently hydrogen, deuterium, halogen, nitro group, nitrile group, substituted or unsubstituted C1~C30 alkyl group, substituted or unsubstituted C2~C30 alkenyl group, substituted or unsubstituted C1~C30 alkoxy group, substituted or unsubstituted C1~C30 sulfide group, substituted or unsubstituted C0~C30 silyl group, substituted or unsubstituted C2~C30 dialkylamine group, substituted or unsubstituted C3~C50 cycloalkyl group, substituted or unsubstituted C1~C50 heterocycloalkyl group, substituted or unsubstituted C3~C50 cycloalkenyl group, substituted or unsubstituted C2~C50 heterocycloalkenyl group, substituted or unsubstituted C5~C50 aryl group, or substituted or unsubstituted C2~C50 heteroaryl group,

[0036] l is an integer from 0 to 6, each independently,

[0037] m is an integer from 0 to 4, each independently,

[0038] In chemical formula 1, * indicates the bonding position with Ar,

[0039] * in Chemical Formulas 1-1 to 1-4 indicates a bonding position with L1.

[0040] In addition, in one embodiment of the present invention,

[0041] An organic light-emitting device containing the compound for a capping layer described above is provided.

[0042] A compound for a capping layer according to one embodiment of the present invention has an arylamine structure having a naphthobenzofuran group with a linker extension on one side and a heteroaryl substituent with a high polarizability on the other side, thereby having a wide band gap with low light absorption in the visible light region and maintaining a high refractive index while simultaneously increasing the absorption wavelength in the ultraviolet region.

[0043] In addition, when the compound for the capping layer is introduced into the capping layer, an organic light-emitting device with high color purity, high efficiency, and long lifespan can be realized.

[0044] Additionally, the intermolecular thin film arrangement is improved through the expansion of the connector, so a higher refractive index can be secured.

[0045] In addition, it can not only improve stability from external air and moisture, but also has high Tg and high Td, so it can effectively prevent intermolecular recrystallization and maintain a stable thin film from heat generated during operation of an organic light-emitting device, so it can be even more effective in increasing external quantum efficiency and improving lifespan.

[0046] The above effects and additional effects are described in detail below.

[0047] Figure 1 is a schematic cross-sectional view showing the configuration of an organic light-emitting device according to one embodiment of the present invention.

[0048] Figure 2 shows the results of measuring the absorption intensity within the wavelength range of 360 nm to 500 nm of a compound according to one embodiment of the present invention and a comparative compound.

[0049] **Explanation of symbols**

[0050] 100: Substrate

[0051] 200: Hole injection layer

[0052] 300: Hole transport layer

[0053] 400: Emissive layer

[0054] 500: Electron transport layer

[0055] 600: Electron injection layer

[0056] 1000: 1st electrode

[0057] 2000: Second electrode

[0058] 3000: Capping layer

[0059] Before describing the present invention in detail below, it is important to understand that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to limit the scope of the present invention, which is limited solely by the scope of the appended claims. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art.

[0060] Throughout this specification and claims, unless otherwise stated, the terms "comprise," "comprises," and "comprising" are used to mean including a stated item, step, or group of items, and steps, but not to the exclusion of any other item, step, or group of items, or group of steps.

[0061] Throughout this specification and claims, the term "aryl" means a C5-50 aromatic hydrocarbon ring group, for example, an aromatic ring such as phenyl, benzyl, naphthyl, biphenyl, terphenyl, fluorene, phenanthrenyl, triphenylenyl, perylenyl, chrysenyl, fluoranthenyl, benzofluorenyl, benzotriphenylenyl, benzocrysenyl, anthracenyl, stilbenyl, pyrenyl, etc., and "heteroaryl" means a C2-50 aromatic ring containing at least one heteroatom, for example, pyrrolyl, pyrazinyl, pyridinyl, indolyl, isoindolyl, furyl, benzofuranyl, isobenzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, quinolyl, isoquinolyl, quinoxalinyl, carbazolyl, It can mean to include a heterocyclic group formed from phenanthridinyl, acridinyl, phenanthrolinyl, thienyl, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, triazine ring, indole ring, quinoline ring, acridine ring, pyrrolidine ring, dioxane ring, piperidine ring, morpholine ring, piperazine ring, carbazole ring, furan ring, thiophene ring, oxazole ring, oxadiazole ring, benzofuran ring, thiazole ring, thiadiazole ring, benzothiophene ring, triazole ring, imidazole ring, benzoimidazole ring, pyran ring, dibenzofuran ring, etc. In addition, the term "arylene" means that in the above aryl group, hydrogen is replaced by a direct bond to become a divalent substituent, and specific examples are not limited as long as the above-described aryl structure becomes a divalent substituent. Likewise, the term "heteroarylene" means that in the above heteroaryl group, hydrogen is replaced by a direct bond to become a divalent substituent, and specific examples are not limited as long as the above-described heteroaryl structure becomes a divalent substituent.

[0062] Also, in the chemical formula, Ar x(where x is an integer) means a substituted or unsubstituted C6~C50 aryl group, or a substituted or unsubstituted C2~C50 heteroaryl group, unless specifically defined, and L x (where x is an integer) means a direct bond, a substituted or unsubstituted C6~C50 arylene group, or a substituted or unsubstituted C2~C50 heteroarylene group, unless specifically defined, and R x (wherein x is an integer) means, unless specifically defined, 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 sulfide group, a substituted or unsubstituted C6~C50 aryl group, or a substituted or unsubstituted C2~C50 heteroaryl group.

[0063] Throughout this specification and claims, the term "substituted or unsubstituted" means a deuterium, a halogen, an amino group, a cyano group, a nitrile group, a nitro group, a nitroso group, a sulfamoyl group, an isothiocyanate group, a thiocyanate group, a carboxyl group, a carbonyl group, or a C1-C30 alkyl group, a C1-C30 alkylsulfinyl group, a C1-C30 alkylsulfonyl group, a C1-C30 alkylsulfanyl group, a C1-C12 fluoroalkyl group, a C2-C30 alkenyl group, a C1-C30 alkoxy group, a C1-C12 N-alkylamino group, a C2-C20 N,N-dialkylamino group, a substituted or unsubstituted C1-C30 sulfide group, a C1-C6 N-alkylsulfamoyl group, a C2-C12 It may mean that it is substituted or unsubstituted with one or more groups selected from the group consisting of N,N-dialkylsulfamoyl group, C0~C30 silyl group, C3~C20 cycloalkyl group, C3~C20 heterocycloalkyl group, C6~C50 aryl group, and C3~C50 heteroaryl group. In addition, the same symbol may have the same meaning throughout the specification of this application unless specifically mentioned.

[0064] Meanwhile, matters described in the specification with the above-defined terms such as “aryl,” “heteroaryl,” “arylene,” “heteroarylene,” and “substituted” are also considered to be described with the examples and combinations thereof listed above, and therefore, the terms may be replaced with or later corrected by the examples and combinations thereof listed above.

[0065] In addition, when the ranges such as "C2~C50", "0 to 7", etc. are described in this specification, even if there is no special description, they can be reduced to various ranges within the described range and are considered to be described in this specification. For example, C2~C50 is considered to describe various reduction ranges such as C2~C50, C5~C50, C6~C30, C6~C20, C6~C15, C6~C10, C12~C30 together with C2~C50. Therefore, the description of numerical ranges in this specification may be reduced or corrected in the future.

[0066] Meanwhile, various embodiments of the present invention may be combined with any other embodiments unless explicitly stated otherwise. Hereinafter, embodiments of the present invention and their resulting effects will be described.

[0067] An organic light-emitting device according to an embodiment of the present invention may be an organic light-emitting device including a capping layer. Specifically, an organic light-emitting device according to an embodiment of the present invention may include a first electrode, a second electrode, one or more organic layers interposed on the inner side of the first electrode and the second electrode, and a capping layer disposed on the outer side of at least one of the first electrode and the second electrode and containing a compound for a capping layer of the present invention.

[0068] As a specific example of a compound for a capping layer of the present invention, a compound for a capping layer represented by the following chemical formula 1 can be mentioned.

[0069] <Chemical Formula 1>

[0070]

[0071] <Chemical Formula 1-1>

[0072]

[0073] <Chemical Formula 1-2>

[0074]

[0075] <Chemical Formula 1-3>

[0076]

[0077] <Chemical Formula 1-4>

[0078]

[0079] In the above chemical formula 1 and chemical formula 1-1 to chemical formula 1-4,

[0080] Ar1 is selected from the chemical formulas 1-1 to 1-4,

[0081] X is independently O or S,

[0082] X1 to X8 are each independently C, CR, or N, provided that at least one of X1 to X8 is N,

[0083] Y is O, S, or NR,

[0084] Z1 to Z7 are each independently C, CR, or N,

[0085] Ar2 is a substituted or unsubstituted C2~C50 heteroaryl group,

[0086] Ar is a substituted or unsubstituted C5~C50 arylene group, a substituted or unsubstituted C2~C50 heteroarylene group, or a combination thereof,

[0087] L1 and L2 are each independently a direct bond, a substituted or unsubstituted C5~C50 arylene group, a substituted or unsubstituted C2~C50 heteroarylene group, or a combination thereof,

[0088] R, R1 and R2 are each independently hydrogen, deuterium, halogen, nitro group, nitrile group, substituted or unsubstituted C1~C30 alkyl group, substituted or unsubstituted C2~C30 alkenyl group, substituted or unsubstituted C1~C30 alkoxy group, substituted or unsubstituted C1~C30 sulfide group, substituted or unsubstituted C0~C30 silyl group, substituted or unsubstituted C2~C30 dialkylamine group, substituted or unsubstituted C3~C50 cycloalkyl group, substituted or unsubstituted C1~C50 heterocycloalkyl group, substituted or unsubstituted C3~C50 cycloalkenyl group, substituted or unsubstituted C2~C50 heterocycloalkenyl group, substituted or unsubstituted C5~C50 aryl group, or substituted or unsubstituted C2~C50 heteroaryl group,

[0089] l is an integer from 0 to 6, each independently,

[0090] m is an integer from 0 to 4, each independently,

[0091] In chemical formula 1, * indicates the bonding position with Ar,

[0092] * in Chemical Formulas 1-1 to 1-4 indicates a bonding position with L1.

[0093] Meanwhile, when the above Ar2 is a heteroaryl group, it may be a substituted or unsubstituted C2~C22 heteroaryl group, and specifically, it may be a substituted or unsubstituted C7~22 heteroaryl group.

[0094] Meanwhile, when the Ar is an arylene group, it may be a substituted or unsubstituted C6~C22 arylene group. In addition, when the Ar is a heteroarylene group, it may be a substituted or unsubstituted C2~C22 heteroarylene group, and specifically, it may be a substituted or unsubstituted C5~C22 heteroarylene group.

[0095] Meanwhile, when at least one of the above L1 and L2 is an arylene group, each may independently be a substituted or unsubstituted C6 to C18 arylene group. In addition, when at least one of the above L1 and L2 is a heteroarylene group, each may independently be a substituted or unsubstituted C2 to C22 heteroarylene group.

[0096] Meanwhile, in the chemical formula 1 and the following chemical formulas, the substituents in the case of substitution include deuterium, halogen, amino group, cyano group, nitrile group, nitro group, nitroso group, sulfamoyl group, isothiocyanate group, thiocyanate group, carboxyl group, carbonyl group, or C1~C30 alkyl group, C1~C30 alkylsulfinyl group, C1~C30 alkylsulfonyl group, C1~C30 alkylsulfanyl group, C1~C12 fluoroalkyl group, C2~C30 alkenyl group, C1~C30 alkoxy group, C1~C12 N-alkylamino group, C2~C20 N,N-dialkylamino group, substituted or unsubstituted C1~C30 sulfide group, C1~C6 N-alkylsulfamoyl group, C2~C12 Examples of the substituents include N,N-dialkylsulfamoyl groups, C0~C30 silyl groups, C3~C20 cycloalkyl groups, C3~C20 heterocycloalkyl groups, C6~C50 aryl groups, and C3~C50 heteroaryl groups. More specific substituents include deuterium, halogen, nitrile groups, C1~C10 alkyl groups, C1~C10 alkoxy groups, C1~C10 alkylthio groups, C1~C10 fluoroalkyl groups in which hydrogen is replaced by fluorine, C6~C20 aryl groups, and C3~C20 heteroaryl groups.

[0097] As a specific example compound of the capping layer compound of the present invention, the above chemical formula 1 may include a capping layer compound represented by the following chemical formula 2 or chemical formula 3.

[0098] <Chemical Formula 2>

[0099]

[0100] <Chemical Formula 3>

[0101]

[0102] In the above chemical formulas 2 and 3,

[0103] The same symbols as in the above chemical formula 1 and chemical formulas 1-1 to 1-4 have the same definitions.

[0104] The compound for the capping layer of the present invention represented by the above chemical formula 2 is effective in minimizing the bulky characteristics of the core and improving the refractive index with a linear bonding position.

[0105] As a specific example compound of the capping layer compound of the present invention, the chemical formula 1 may include a capping layer compound represented by any one of the following chemical formulas 4 to 7.

[0106] <Chemical Formula 4>

[0107]

[0108] <Chemical Formula 5>

[0109]

[0110] <Chemical Formula 6>

[0111]

[0112] <Chemical Formula 7>

[0113]

[0114] In the above chemical formulas 4 to 7,

[0115] The same symbols as in the above chemical formula 1 and chemical formulas 1-1 to 1-4 have the same definitions.

[0116] The capping layer compound of the present invention represented by the above chemical formulas 4 to 7 has excellent thin film arrangement at specific bonding positions of substituents, and is effective in improving refractive index.

[0117] In addition, in the chemical formulas 1 to 7,

[0118] The above Ar can each independently be a phenylene group, a pyridylene group, a naphthalene group, a quinoline group, an isoquinoline group, or a combination thereof. This minimizes the bulky nature of the linking group, thereby maintaining a high refractive index and at the same time, improving thermal stability.

[0119] In addition, in the chemical formulas 1 to 7,

[0120] The above Ar2 may be a condensed heteroaryl group having a condensed ring structure of two, three, or four rings. This allows for a condensed ring group with minimized bulkiness, thereby enabling excellent intermolecular thin film arrangement and high refractive index, while simultaneously increasing absorption intensity in the ultraviolet region.

[0121] In addition, the above Ar2 may have one to three heteroatoms of O, S, and N. This allows for a high refractive index while minimizing absorption in the blue region.

[0122] The above Ar2 can be specifically selected from the group consisting of a quinoline group, an isoquinoline group, a benzofuran group, a benzothiophene group, a benzoxazole group, a benzothiazole group, an imidazopyridine group, a naphthobenzofuran group, and a naphthobenzothiophene group. This allows for a high refractive index, minimizes absorption in the blue region, and simultaneously lowers the deposition temperature, which is advantageous for forming a thin film with excellent thermal stability and stability.

[0123] In addition, in the chemical formulas 1 to 7 (including chemical formulas 1-4),

[0124] All Xs can be oxygen. This minimizes bulkiness, allowing for high refractive index while simultaneously minimizing absorption in the blue region. In addition, by minimizing molecular weight, it allows for low deposition temperature, thereby improving thermal stability.

[0125] Meanwhile, in the chemical formulas 1 to 7,

[0126] The above -L2-Ar2 may be any one of the following chemical structural formulae A-1 to A-24 or may include any one of the following chemical structural formulae A-1 to A-24.

[0127]

[0128]

[0129]

[0130] In the above chemical structural formulas A-1 to A-24,

[0131] q and w are each independently integers from 0 to 3.

[0132] As described above, the capping layer compound of the present invention has at least one structure among chemical structural formulas A-1 to A-24, thereby excellently realizing high refractive index, stability of intermolecular thin film arrangement, increased absorption intensity in the ultraviolet region, and minimized absorption in the blue region.

[0133] In addition, when the compound for the capping layer represented by the above chemical formula 1 is deposited to a thickness of 30 nm to 120 nm to manufacture a deposition film and the refractive index is measured at a wavelength of 450 nm, the compound may have a high refractive index of 2.45 or more, specifically 2.50 or more, and more specifically 2.55 or more, at any one thickness in the thickness range of 30 nm to 120 nm.

[0134] In addition, the above chemical formula 1 may be a capping layer compound represented by any one of the compounds below. The compounds below are merely examples for explaining the present invention, and the present invention is not limited thereto.

[0135]

[0136]

[0137]

[0138]

[0139]

[0140]

[0141]

[0142]

[0143]

[0144]

[0145]

[0146]

[0147]

[0148]

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155]

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162]

[0163]

[0164]

[0165]

[0166]

[0167]

[0168]

[0169]

[0170] .

[0171] One embodiment of the compound of the present invention can be synthesized according to the following schematic reaction scheme.

[0172] <Reaction Scheme 1>

[0173]

[0174] In another embodiment, the present invention provides a capping layer for an organic light-emitting device containing the compound for a capping layer described above. The capping layer may have a refractive index of 2.45 or more, specifically 2.50 or more, and more specifically 2.55 or more at a wavelength of 450 nm, at a thickness in a range of 30 nm to 120 nm.

[0175] In addition, the present invention provides, as another embodiment, an organic light-emitting device having a capping layer, wherein the capping layer contains the compound for the capping layer described above.

[0176] Next, an organic light-emitting device according to one embodiment of the present invention will be described in detail.

[0177] According to one embodiment of the present invention, an organic light-emitting device may be configured to include a first electrode, a second electrode, one or more organic layers interposed on the inner side of the first electrode and the second electrode, and a capping layer, wherein the capping layer may be disposed on the outer side of at least one of the first electrode and the second electrode.

[0178] Specifically, among the two sides of the first electrode or the second electrode, the side adjacent to the organic layer interposed between the first electrode and the second electrode 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 capping layer is disposed on the outer side of the first electrode, the first electrode is interposed between the capping layer and the organic layer, and when the capping layer is disposed on the outer side of the second electrode, the second electrode is interposed between the capping layer and the organic layer.

[0179] In addition, according to one embodiment of the present invention, the organic light-emitting device may have one or more layers of various organic materials interposed on the inner side of the first electrode and the second electrode, and a capping layer may be formed on the outer side of at least one of the first electrode and the second electrode. That is, the capping layer may be formed on both the outer side of the first electrode and the outer side of the second electrode, or may be formed only on the outer side of the first electrode or the outer side of the second electrode.

[0180] At this time, the capping layer may include a compound for a capping layer according to the present invention, and may include a single compound for a capping layer according to the present invention, two or more compounds, or a combination of known compounds.

[0181] The thickness of the capping layer may have a value of 100 Å to 2000 Å.

[0182] Meanwhile, the capping layer may have a composite capping layer structure in which a first capping layer having a relatively low refractive index and a second capping layer having a higher refractive index than the first capping layer are laminated, and in this case, the compound for a capping layer according to the present invention may be included in the second capping layer. The lamination order of the first capping layer and the second capping layer is not limited, and the first capping layer may be disposed outside the second capping layer, or conversely, the second capping layer may be disposed outside the first capping layer. As a specific example, the second capping layer may be interposed between the first capping layer and the first electrode or the second electrode, and specifically, the second capping layer may have a structure in contact with the first capping layer and the first electrode, or the first capping layer and the second electrode.

[0183] Additionally, it may be a multilayer structure in which a plurality of first capping layers and a plurality of second capping layers are laminated. In this case, the first capping layers and the second capping layers may be laminated alternately, and the lamination order is not limited as described above. The first capping layer may be arranged on the outside relative to the second capping layer, or conversely, the second capping layer may be arranged on the outside relative to the first capping layer.

[0184] Additionally, the first capping layer may have a refractive index of 1.55 or less, specifically 1.53 or less, and more specifically 1.51 or less at a wavelength of 450 nm at a thickness ranging from 300 to 1,200 Å. The second capping layer may have a refractive index of 2.45 or more, specifically 2.50 or more, and more specifically 2.55 or more at a wavelength of 450 nm at a thickness ranging from 300 to 1,200 Å.

[0185] The total thickness of the first capping layer may be in the range of 50 Å to 2000 Å, and the total thickness of the second capping layer may be in the range of 50 Å to 2000 Å.

[0186] Meanwhile, the capping layer may have a refractive index gradient. The refractive index gradient may gradually decrease toward the outside, or may gradually increase toward the outside. To this end, the capping layer may be formed by gradually varying the concentration of the capping layer compound according to the present invention, thereby implementing a refractive index gradient in the capping layer.

[0187] Meanwhile, the organic layer may generally include a hole transport layer, a light emitting layer, and an electron transport layer that constitute a light emitting portion, but may not be limited thereto.

[0188] More specifically, an organic light-emitting device according to one embodiment of the present invention may include at least one organic layer constituting a light-emitting portion, such as a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL), between a first electrode (anode) and a second electrode (cathode). Optionally, a hole blocking layer (HBL, not shown) or an electron transport auxiliary layer may be further included between the emission layer (EML) and the electron transport layer (ETL), and an electron blocking layer (EBL, not shown) or an emission auxiliary layer may be further included between the hole transport layer (HTL) and the emission layer (EML).

[0189] Fig. 1 is a cross-sectional view schematically showing the configuration of an organic light-emitting device according to an embodiment of the present invention. An organic light-emitting device according to one embodiment of the present invention can be manufactured as described in Fig. 1.

[0190] As shown in FIG. 1, the organic light-emitting device may have 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 capping layer (3000) are sequentially stacked from the bottom. Here, although not shown, the capping layer (3000) may be a single capping layer as described above, or may have a structure in which a first capping layer and a second capping layer are stacked. In addition, a third capping layer having a different refractive index from the first and second capping layers may be further added and stacked, and the structure is not limited thereto. In addition, the capping layer may have a form in which a refractive index gradient exists. The refractive index gradient may gradually decrease toward the outside, or may gradually increase toward the outside.

[0191] Here, the substrate (100) may be a substrate generally used in organic light-emitting devices, 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 waterproofing.

[0192] In addition, the first electrode (1000) is used as a hole injection electrode for hole injection of an organic light-emitting device. The first electrode (1000) is manufactured using a material having a low work function to enable hole injection, and may be formed of a transparent material such as indium tin oxide (ITO), indium zinc oxide (IZO), or graphene.

[0193] In addition, the hole injection layer (200) can be formed by depositing a hole injection layer material on the upper portion of the first electrode (1000) by a method such as a vacuum deposition method, a spin coating method, a casting method, an LB (Langmuir-Blodgett) method, etc. In the case of forming the hole injection layer (200) by the vacuum deposition method, the deposition conditions vary depending on the compound used as the material of the hole injection layer (200), the structure and thermal characteristics of the desired hole injection layer (200), etc., but are generally a deposition temperature of 50-500°C, a deposition temperature of 10 -8 10 inland -3 The vacuum level can be appropriately selected from the range of 10 torr, the deposition rate of 0.01 to 100 Å / sec, and the layer thickness of 10 Å to 5 ㎛. Meanwhile, a charge generation layer can be additionally deposited on the surface of the hole injection layer (200) as needed. A typical material can be used as the charge generation layer material, and HATCN can be given as an example.

[0194] In addition, the hole transport layer (300) can be formed by depositing a hole transport layer material on top of the hole injection layer (200) by a method such as vacuum deposition, spin coating, casting, or LB method. When the hole transport layer (300) is formed by the vacuum deposition method, the deposition conditions vary depending on the compound used, but it is generally preferable to select conditions that are almost the same as those for forming the hole injection layer (200). The hole transport layer (300) can be formed using a known compound. The hole transport layer (300) can have one or more layers, and although not shown in FIG. 1, a light-emitting auxiliary layer can be additionally formed on top of the hole transport layer (300).

[0195] In addition, 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 by a method such as vacuum deposition, spin coating, casting, or LB method. When the light-emitting layer (400) is formed by the vacuum deposition method, the deposition conditions vary depending on the compound used, but it is generally preferable to select conditions that are almost the same as those for forming the hole injection layer (200). The light-emitting layer material can use a known compound as a host or dopant. The dopant is not limited, but a phosphorescent or fluorescent dopant can be used together to form the light-emitting layer. For example, as a fluorescent dopant, BD142 (N6,N12-bis(3,4-dimethylphenyl)-N6,N12-dimethyethylchrysene-6,12-diamine) can be used, and as a phosphorescent dopant, green phosphorescent dopant Ir(ppy)3 (tris(2-phenylpyridine) iridium), blue phosphorescent dopant F2Irpic (iridium(III) bis[4,6-difluorophenyl)-pyridinato-N,C2'] picolinate), and red phosphorescent dopant RD61 of UDC can be co-vacuum deposited (doped). The doping concentration of the dopant is not particularly limited, but it is preferable that the dopant is doped in an amount of 0.01 to 15 parts by weight relative to 100 parts by weight of the host. If the dopant content is less than 0.01 parts by weight, there is a problem that the color development is not properly achieved due to insufficient dopant content, and if it exceeds 15 parts by weight, there is a problem that the efficiency is rapidly reduced due to concentration quenching.

[0196] Here, when a phosphorescent dopant is used together with the light-emitting layer material, a hole blocking material (HBL) may be additionally laminated on the upper part of the light-emitting layer (400) through vacuum deposition or spin coating to prevent triplet excitons or holes from diffusing to the electron transport layer (500). The hole blocking material that can be used is not particularly limited, and a known material may be arbitrarily selected and used. Examples thereof include oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, or hole blocking materials described in Japanese Patent Application Laid-Open No. 11-329734 (A1), and representative examples thereof include Balq (bis(8-hydroxy-2-methylquinolinolnato)-aluminum biphenoxide), phenanthroline compounds (e.g., UDC's BCP (basocuproin)), etc. 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.

[0197] In addition, the electron transport layer (500) is formed on the upper part of the light-emitting layer (400) and can be formed by a method such as a vacuum deposition method, a spin coating method, or a casting method. The deposition conditions of the electron transport layer (500) vary depending on the compound used, but it is generally preferable to select conditions that are almost the same as those for forming the hole injection layer (200). As a typical known material, for example, a quinoline derivative, particularly tris(8-quinolinolato)aluminum (Alq3), or ET4(6,6'-(3,4-dimesityl-1,1-dimethyl-1H-silol-2,5-diyl)di-2,2'-bipyridine) can be used.

[0198] Furthermore, the electron injection layer (600) can be formed by depositing an electron injection layer material on top of the electron transport layer (500), and can be formed by a vacuum deposition method, spin coating method, casting method, or the like. As the electron injection layer material, known materials such as LiF, NaCl, CsF, Li2O, and BaO can be used.

[0199] In addition, the second electrode (2000) is used as an electron injection electrode and can be formed on the upper part of the electron injection layer (600) by a method such as vacuum deposition or sputtering. Various metals can be used as the material of the second electrode (2000). Specific examples include, but are not limited to, materials such as lithium (Li), aluminum (Al), gold (Au), silver (Ag), magnesium (Mg), aluminum-lithium (Al-Li), calcium (Ca), magnesium-indium (Mg-In), and magnesium-silver (Mg-Ag). In addition, a transparent electron injection electrode using ITO or IZO can be used to obtain a front light-emitting element.

[0200] The organic light-emitting device of the present invention may be an organic light-emitting device having a structure including the first electrode (1000), hole injection layer (200), hole transport layer (300), light-emitting layer (400), electron transport layer (500), electron injection layer (600), second electrode (2000), and capping layer (3000) described above, as well as an organic light-emitting device having various structures, and may additionally include one or two intermediate layers as needed.

[0201] Meanwhile, the thickness of each organic layer formed according to the present invention can be adjusted according to the required degree, and specifically, it can be 1 to 5,000 Å, and more specifically, 50 to 2,000 Å.

[0202] The capping layer (3000) may be formed on the outer surface of both sides of the first electrode (1000) where the hole injection layer (200) is not formed, as shown in FIG. 1. In addition, it may also be formed on the outer surface of both sides of the second electrode (2000) where the electron injection layer (600) is not formed, but is not limited thereto. The capping layer (3000) may be formed by a deposition process, and the thickness of the capping layer (3000) may be 100 to 3,000 Å, and more specifically, 300 to 2,000 Å. By controlling the thickness in this manner, the transmittance of the capping layer (3000) may be prevented from decreasing.

[0203] In addition, although not shown in FIG. 1, according to one embodiment of the present invention, an organic layer having various functions may be additionally formed between the capping layer (3000) and the first electrode (1000) or between the capping layer (3000) and the second electrode (2000). Alternatively, an organic layer having various functions may be additionally formed on the upper portion (outer surface) of the capping layer (3000), and one or more separate functional layers may be inserted and present in the middle of the capping layer (3000), but is not limited thereto.

[0204] Hereinafter, the present invention will be described in more detail through examples of compound synthesis and organic light-emitting device synthesis according to one embodiment of the present invention. The following synthesis examples and examples are merely illustrative of the present invention, and the scope of the present invention is not limited to the examples below.

[0205] Synthesis Example 1: Synthesis of Compound 2

[0206]

[0207] In a round-bottomed flask, 12.0 g of 3-(4-bromophenyl)naphtho[2,3-b]benzofuran, 10.0 g of bis(4-(quinolin-3-yl)phenyl)amine, 4.0 g of t-BuONa, 30.2 g of Pd2(dba), and 0.2 ml of (t-Bu)3P were dissolved in 200 ml of toluene and stirred under reflux. The reaction was confirmed by TLC, and the reaction was terminated after adding water. The organic layer was extracted with MC, filtered under reduced pressure, and then purified by column chromatography and recrystallization to obtain 13.0 g of compound 2 (yield 68%).

[0208] m / z: 715.26 (100.0%), 716.27 (56.7%), 717.27 (16.0%), 718.27 (3.1%), 716.26 (1.1%)

[0209] Synthesis Example 2: Synthesis of Compound 3

[0210]

[0211] Compound 3 was synthesized using bis(4-(quinolin-6-yl)phenyl)amine instead of bis(4-(quinolin-3-yl)phenyl)amine in the same manner as in Synthesis Example 1. (Yield: 65%)

[0212] m / z: 715.26 (100.0%), 716.27 (56.7%), 717.27 (16.0%), 718.27 (3.1%), 716.26 (1.1%)

[0213] Synthesis Example 3: Synthesis of Compound 7

[0214]

[0215] Compound 7 was synthesized using bis(4-(quinolin-2-yl)phenyl)amine instead of bis(4-(quinolin-3-yl)phenyl)amine in the same manner as in Synthesis Example 1. (Yield 70%)

[0216] m / z: 715.26 (100.0%), 716.27 (56.7%), 717.27 (16.0%), 718.27 (3.1%), 716.26 (1.1%)

[0217] Synthesis Example 4: Synthesis of Compound 8

[0218]

[0219] Compound 8 was synthesized using bis(4-(benzofuran-2-yl)phenyl)amine instead of bis(4-(quinolin-3-yl)phenyl)amine in the same manner as in Synthesis Example 1. (Yield: 70%)

[0220] m / z: 693.23 (100.0%), 694.23 (54.6%), 695.24 (14.6%), 696.24 (2.9%)

[0221] Synthesis Example 5: Synthesis of Compound 9

[0222]

[0223] Compound 9 was synthesized using bis(4-(benzo[b]thiophen-2-yl)phenyl)amine instead of bis(4-(quinolin-3-yl)phenyl)amine in the same manner as in Synthesis Example 1 (yield 73%).

[0224] m / z: 725.18 (100.0%), 726.19 (54.5%), 727.19 (15.8%), 727.18 (9.1%), 728.18 (5.0%), 728.19 (2.9%), 726.18 (2.0%), 729.19 (1.4%)

[0225] Synthesis Example 6: Synthesis of Compound 12

[0226]

[0227] Compound 12 was synthesized using bis(4-(imidazo[1,2-a]pyridin-2-yl)phenyl)amine instead of bis(4-(quinolin-3-yl)phenyl)amine in the same manner as in Synthesis Example 1 (yield 63%).

[0228] m / z: 693.25 (100.0%), 694.26 (52.3%), 695.26 (13.6%), 696.26 (2.5%), 694.25 (1.8%)

[0229] Synthesis Example 7: Synthesis of Compound 13

[0230]

[0231] Compound 13 was synthesized using bis(naphtho[2,3-b]benzofuran-3-yl)amine instead of bis(4-(quinolin-3-yl)phenyl)amine in the same manner as in Synthesis Example 1 (yield 69%).

[0232] m / z: 741.23 (100.0%), 742.23 (58.9%), 743.24 (17.0%), 744.24 (3.6%)

[0233] Synthesis Example 8 to Synthesis Example 30

[0234] Compounds were synthesized using starting materials 1 and 2 in Tables 1 to 3 below instead of bis(4-(quinolin-3-yl)phenyl)amine and 3-(4-bromophenyl)naphtho[2,3-b]benzofuran in the same manner as in Synthesis Example 1.

[0235]

[0236]

[0237]

[0238] Manufacturing of organic light-emitting devices

[0239] FIG. 1 illustrates the structure of a typical organic light-emitting device. The present invention, as an example, has the structure of the organic light-emitting device illustrated in FIG. 1, but additionally introduces an electron injection layer (not shown) between the electron transport layer (500) and the cathode (2000). Specifically, the manufactured organic light-emitting device is laminated in the following order from the bottom: anode (hole injection electrode (1000)) / hole injection layer (200) / hole transport layer (300) / light-emitting layer (400) / electron transport layer (500) / electron injection layer (600) / cathode (electron injection electrode (2000)) / capping layer (3000).

[0240] When manufacturing an organic light-emitting device, the substrate (10) may be a transparent glass substrate or a flexible plastic substrate.

[0241] The hole injection electrode (1000) is used as an anode for hole injection in an organic light-emitting device. A material having a low work function is used to enable hole injection, and may be formed of a transparent material such as indium tin oxide (ITO), indium zinc oxide (IZO), or graphene.

[0242] The materials listed in Table 4 below were used for the hole injection layer (200), hole transport layer (300), light emitting layer (400), electron transport layer (500), electron injection layer (600), and capping layer.

[0243] Additionally, a cathode (2000) for electron injection was formed on the electron injection layer (600). Various metals can be used as the cathode. Specific examples include materials such as aluminum, gold, silver, magnesium, and magnesium-silver alloy.

[0244]

[0245] Example 1

[0246] An indium tin oxide (ITO) substrate having a reflective layer including silver (Ag) formed thereon was ultrasonically washed in distilled water. After washing with distilled water, it was ultrasonically washed with a solvent such as isopropyl alcohol, acetone, or methanol and dried. Then, HT01 doped with 3 wt% NDP9 was deposited on the ITO substrate as a hole injection layer (100 Å) and HT01 was deposited as a hole transport layer (1400 Å). Then, host BH01 doped with 3 wt% dopant BD01 was deposited as an emission layer (250 Å). Then, a mixture of ET01 and Liq (1:1, wt. / wt.) was deposited as an electron transport layer (300 Å), and LiF was deposited to a thickness of 10 Å to form an electron injection layer. Subsequently, MgAg was deposited to a thickness of 15 nm to form a cathode. The compound prepared in Synthesis Example 1 was deposited as a capping layer on the above cathode to a thickness of 600 Å. An organic light-emitting device was manufactured by encapsulating the device in a glove box.

[0247] Examples 2 to 30

[0248] An organic light-emitting device was manufactured using the same method as in Example 1, but using the compounds manufactured in Synthesis Examples 2 to 30 as a capping layer.

[0249] Comparative Examples 1 to 6

[0250] An organic light-emitting device was manufactured using the same method as in Example 1, but using Comparative Compounds 1 to 6 shown in Table 5 below as a capping layer.

[0251]

[0252] <Experimental Example 1> Performance Evaluation of Organic Light-Emitting Diodes

[0253] By applying voltage using a Keithley 2400 source measurement unit to inject electrons and holes and measuring the luminance when light is emitted using a Konica Minolta spectroradiometer (CS-2000), the performance of the organic light-emitting devices of Examples 1, 4 to 7, 12, 16 to 18, 20, 21, 23, 26 and Comparative Examples 1 to 6 was evaluated by measuring the current density and luminance for the applied voltage under atmospheric pressure conditions. The results are shown in Tables 6 and 7.

[0254]

[0255]

[0256] Comparing the examples of the present invention, compared to Comparative Examples 1 to 6, the present invention can have a high refractive index by having an arylamine structure including a naphthobenzofuran with an extended linker, and is effective in improving the refractive index even with a small molecular weight. In addition, by including a heteroaryl substituent with a high polarizability, the refractive index is improved, and at the same time, the absorption wavelength in the ultraviolet region is increased and a stable thin film can be formed with excellent molecular arrangement, thereby ensuring thermal stability and enabling the implementation of a high-efficiency, long-life organic light-emitting device.

[0257] <Experimental Example 2> Evaluation of refractive index

[0258] Using compounds 2, 8, 12, and 75 and comparative compounds 1 to 4, respectively, a 60 nm thick deposition film was produced on a silicon substrate using a vacuum deposition device, and the refractive index at a wavelength of 450 nm was measured using an ellipsometer device (JA Woollam Co. Inc, M-2000X). The results are summarized in Table 8 below.

[0259] @450nmComparative Compound 1Comparative Compound 2Comparative Compound 3Comparative Compound 4Refractive Index, n2.282.412.232.43@450nmCompound 2Compound 8Compound 12Compound 75Refractive Index, n2.552.572.552.59

[0260] As described in Table 8 above, it can be confirmed that compounds 2, 8, 12, and 75 exhibit high refractive indices of 2.45 or higher, specifically 2.50 or higher, and more specifically 2.55 or higher.

[0261] In addition, in light of the device evaluations in Table 6 of examples in which only the capping layer compound was changed, it is predicted that all example compounds and specific compounds of the present invention will have a refractive index equivalent to that of the compounds of the present invention shown in Table 8.

[0262] <Experimental Example 3> Evaluation of absorption intensity in the ultraviolet region

[0263] In the ultraviolet region, using compound 8 and comparative compounds 1 and 3, respectively, a 30 nm thick deposition film was produced on a silicon substrate using a vacuum deposition device, and the absorption coefficient within the wavelength range of 360 nm to 500 nm was measured using an ellipsometer device (JA Woollam Co. Inc, M-2000X), and the results are shown in Fig. 2. Based on the wavelength of 380 nm in the ultraviolet absorption region, the absorption intensity of compound 8 is 1.0 or more, more specifically, 1.1 or more, and more specifically, 1.20 or more, and it can be confirmed that the absorption intensity increases by 30% or more compared to comparative compounds 1 and 3.

[0264] In addition, in light of the device evaluations in Table 6 of examples in which only the capping layer compound was changed, it is predicted that all the example compounds and specific compounds of the present invention will have an absorption intensity in the ultraviolet region equivalent to the absorption intensity in the ultraviolet region of the compounds of the present invention shown in FIG. 2.

Claims

1. A compound for a capping layer represented by the following chemical formula 1: <Chemical Formula 1> <Chemical Formula 1-1> <Chemical Formula 1-2> <Chemical Formula 1-3> <Chemical Formula 1-4> In the above chemical formula 1 and chemical formula 1-1 to chemical formula 1-4, Ar1 is selected from the chemical formulas 1-1 to 1-4, X is independently O or S, X1 to X8 are each independently C, CR, or N, provided that at least one of X1 to X8 is N, Y is O, S, or NR, Z1 to Z7 are each independently C, CR, or N, Ar2 is a substituted or unsubstituted C2~C50 heteroaryl group, Ar is a substituted or unsubstituted C5~C50 arylene group, a substituted or unsubstituted C2~C50 heteroarylene group, or a combination thereof, L1 and L2 are each independently a direct bond, a substituted or unsubstituted C5~C50 arylene group, a substituted or unsubstituted C2~C50 heteroarylene group, or a combination thereof, R, R1 and R2 are each independently hydrogen, deuterium, halogen, nitro group, nitrile group, substituted or unsubstituted C1~C30 alkyl group, substituted or unsubstituted C2~C30 alkenyl group, substituted or unsubstituted C1~C30 alkoxy group, substituted or unsubstituted C1~C30 sulfide group, substituted or unsubstituted C0~C30 silyl group, substituted or unsubstituted C2~C30 dialkylamine group, substituted or unsubstituted C3~C50 cycloalkyl group, substituted or unsubstituted C1~C50 heterocycloalkyl group, substituted or unsubstituted C3~C50 cycloalkenyl group, substituted or unsubstituted C2~C50 heterocycloalkenyl group, substituted or unsubstituted C5~C50 aryl group, or substituted or unsubstituted C2~C50 heteroaryl group, l is an integer from 0 to 6, each independently, m is an integer from 0 to 4, each independently, In chemical formula 1, * indicates the bonding position with Ar, * in Chemical Formulas 1-1 to 1-4 indicates a bonding position with L1.

2. In paragraph 1, The above chemical formula 1 is a compound for a capping layer represented by the following chemical formula 2 or chemical formula 3: <Chemical Formula 2> <Chemical Formula 3> In the above chemical formulas 2 and 3, The same symbols as in the above chemical formula 1 and chemical formulas 1-1 to 1-4 have the same definitions.

3. In paragraph 1, The above chemical formula 1 is a compound for a capping layer represented by any one of the following chemical formulas 4 to 7: <Chemical Formula 4> <Chemical Formula 5> <Chemical Formula 6> <Chemical Formula 7> In the above chemical formulas 4 to 7, The same symbols as in the above chemical formula 1 and chemical formulas 1-1 to 1-4 have the same definitions.

4. In paragraph 1, The above Ar is a compound for a capping layer, which is a phenylene group, a pyridylene group, a naphthalene group, a quinoline group, an isoquinoline group or a combination thereof.

5. In paragraph 1, The above Ar2 is a compound for a capping layer, which is a condensed heteroaryl group having a condensed ring structure of two, three or four rings.

6. In paragraph 1, The above Ar2 is a compound for a capping layer having 1 to 3 heteroatoms of O, S, and N.

7. In paragraph 1, The above Ar2 is a compound for a capping layer selected from the group consisting of a quinoline group, an isoquinoline group, a benzofuran group, a benzothiophene group, a benzoxazole group, a benzothiazole group, an imidazopyridine group, a naphthobenzofuran group, and a naphthobenzothiophene group.

8. In paragraph 1, A compound for a capping layer, wherein X in the above chemical formula 1 and chemical formula 1-4 is both oxygen (O).

9. In paragraph 1, The above -L2-Ar2 is any one of the following chemical structures A-1 to A-24 or a compound for a capping layer comprising any one of the following chemical structures A-1 to A-24: In the above chemical structural formulas A-1 to A-24, q and w are each independently integers from 0 to 3.

10. In paragraph 1, The compound for the capping layer is any one of the following compounds: .

11. In paragraph 1, The compound for the capping layer is a compound for the capping layer having a refractive index of 2.45 or more when the refractive index is measured at a wavelength of 450 nm after depositing the compound for the capping layer to a thickness of 30 nm to 120 nm to manufacture a deposition film.

12. A capping layer for an organic light-emitting device containing the compound for the capping layer of paragraph 1.

13. In paragraph 12, The capping layer is a capping layer for an organic light-emitting device having a refractive index of 2.45 or more at a wavelength of 450 nm at a thickness in a range of 30 nm to 120 nm.

14. An organic light-emitting device having a capping layer containing the compound for the capping layer of paragraph 1.

15. In paragraph 14, The above organic light-emitting device, First electrode; a second electrode; and It comprises one or more organic layers interposed on the inner side of the first electrode and the second electrode, An organic light-emitting device in which the capping layer is disposed on the outer side of at least one of the first electrode and the second electrode.

16. In paragraph 14, An organic light-emitting device wherein the thickness of the capping layer is in the range of 100Å to 2000Å.

17. In paragraph 14, An organic light-emitting device having a refractive index of 2.45 or more at a wavelength of 450 nm at a thickness in the range of 300 to 1,200 Å.

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