KR20210152959A - New compound for capping layer and Organic light emitting diode comprising to the same - Google Patents

Abstract

The present invention provides a compound for a capping layer represented by chemical formula 1, and an organic light emitting device containing the same. When the compound for the capping layer according to an embodiment of the present invention is applied to the capping layer of the organic light emitting device, the organic light emitting device with high color purity, high efficiency, and long life can be realized.

Description

New compound for capping layer and organic light emitting diode comprising the same

The present invention relates to a compound for a capping layer and an organic light emitting device including the same.

A material used as an organic layer in an organic light emitting device may be classified into a light emitting material, a hole injection material, a hole transport material, an electron transport material, an electron injection material, and the like according to a function.

In addition, the light emitting material may be classified into a fluorescent material derived from a singlet excited state of an electron and a phosphorescent material derived from a triplet excited state of an electron according to a light emitting mechanism. can be

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

The driving principle of the organic light emitting diode having the above-described structure is as follows.

When a voltage is applied between the anode and the cathode, holes injected from the anode move to the emission layer via the hole transport layer, and electrons injected from the cathode move to the emission layer via the electron transport layer. The holes and electrons recombine in the emission layer to generate excitons.

Light is generated as this exciton changes from an excited state to a ground state. The efficiency of organic light emitting diodes can be generally divided into internal luminous efficiency and external luminous efficiency. The internal luminous efficiency is related to how efficiently excitons are generated in the organic layer interposed between the first and second electrodes, such as a hole transport layer, a light emitting layer, and an electron transport layer, to achieve light conversion. Theoretically, in the case of fluorescence, 25%, phosphorescence is known to be 100%.

On the other hand, the external luminous efficiency refers to the efficiency at 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 is usually extracted to the outside as about 20% of the internal luminous efficiency. As a method to increase this light extraction, various organic compounds having a refractive index of 1.7 or more have been applied as a capping layer to prevent total reflection and loss of light going out to the outside. Efforts have been made to develop organic compounds having high refractive index and thin film stability.

The present invention is an arylamine compound comprising a heterobicyclic ring containing at least one nitrogen (N) in the form of indolizine or imidazolepyridine, etc., and has a wide band gap and high refractive index that is difficult to absorb in the visible region, At the same time, an object of the present invention is to provide a compound for a capping layer capable of realizing an organic light emitting device with high color purity, high efficiency, and long life by increasing the absorption wavelength in the ultraviolet region, and an organic light emitting device including the same.

In addition, the intermolecular thin film arrangement is excellent, which improves the refractive index, prevents intermolecular recrystallization with high Tg and Td, maintains a stable thin film from heat generated during operation, and protects the device from external air and moisture to improve stability. An object of the present invention is to provide a compound for a capping layer and an organic light emitting device that can increase external quantum efficiency and significantly improve lifespan.

The above tasks and additional tasks will be described in detail below.

In order to solve the above problems, the present invention in one embodiment,

A compound for a capping layer represented by the following formula (1) is provided:

<Formula 1>

(In Formula 1,

X1 to X7 are each independently C, CR or N, wherein each R is 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, or substituted or unsubstituted C6~ C50 aryl group, or substituted or unsubstituted C2~ It is a C50 heteroaryl group, and a plurality of adjacent Rs may or may not form a ring by bonding with each other,

Ar1 and Ar2 are each independently a substituted or unsubstituted C6~ C50 aryl group, or a substituted or unsubstituted C2~C50 heteroaryl group,

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

In addition, the present invention in one embodiment,

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

The compound for a capping layer according to an embodiment of the present invention contains at least one nitrogen (N) in the form of indolizine or imidazole pyridine, etc., but a heterobicyclic ring in which nitrogen (N) is necessarily located at a specific position. The arylamine compound containing the arylamine compound has a wide bandgap and high refractive index that is difficult to absorb in the visible region, and at the same time the absorption wavelength in the ultraviolet region is increased. A light emitting device can be implemented.

In addition, the refractive index is improved due to the excellent arrangement of the intermolecular thin film.

In addition, since it has high Tg and high Td, it prevents intermolecular recrystallization, maintains a stable thin film from heat generated when driving an organic light emitting device, and protects the device from external air and moisture to improve stability, external quantum efficiency This increases and the lifespan is significantly improved.

The above effects and additional effects will be described in detail below.

1 is a schematic cross-sectional view of a layer structure of an organic light emitting device according to an embodiment of the present invention.
2 is a graph of measuring absorption wavelengths within the range of 340 nm to 460 nm.

Prior to describing the present invention in detail below, it is to be understood that the terminology used herein is for the purpose of describing specific embodiments and is not intended to limit the scope of the present invention, which is limited only by the appended claims. shall. All technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art, unless otherwise stated.

Throughout this specification and claims, unless stated otherwise, the term comprise, comprises, comprising is meant to include the stated object, step or group of objects, and steps, and any other object. It is not used in the sense of excluding a step or a group of objects or groups of steps.

Throughout this specification and claims, the term "aryl" refers to a C5-50 aromatic hydrocarbon ring group such as phenyl, benzyl, naphthyl, biphenyl, terphenyl, fluorene, phenanthrenyl, triphenyl is meant to include aromatic rings such as renyl, perylenyl, chrysenyl, fluoranthenyl, benzofluorenyl, benzotriphenylenyl, benzochrysenyl, anthracenyl, stilbenyl, pyrenyl, and the like, "heteroaryl" is a C2-50 aromatic ring containing at least one hetero element, for example, pyrrolyl, pyrazinyl, pyridinyl, indolyl, isoindolyl, furyl, benzofuranyl, isobenzofuranyl, dibenzo furanyl, benzothiophenyl, dibenzothiophenyl, quinolyl, isoquinolyl, quinoxalinyl, carbazolyl, phenanthridinyl, acridinyl, phenanthrolinyl, thienyl, and pyridine ring, pyrazine ring, pyridine Midine 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, dibenzo It may mean including a heterocyclic group formed from a furan ring and the like.

In addition, in the 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 otherwise defined, and L _x ( Here, 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 otherwise defined, and R _x (where x is integer) is 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 C6~ C50 aryl group, or substituted or unsubstituted C2~ C50 heteroaryl group.

Throughout this specification and claims, the term "substituted or unsubstituted" refers to deuterium, halogen, amino group, cyano group, nitrile group, nitro group, nitroso group, sulfamoyl group, isothiocyanate group, thiocyanate group , carboxyl group, or C1 to C30 alkyl group, C1 to C30 alkylsulfinyl group, C1 to C30 alkylsulfonyl group, C1 to C30 alkylsulfanyl group, C1 to C12 fluoroalkyl group, C2 to 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 N,N-dialkylsulfamoyl group, C3-C30 silyl group, C3-C20 cycloalkyl group, C3-C20 heterocycloalkyl group, C6-C50 aryl group and C3-C50 heteroaryl group It may mean unsubstituted or substituted with one or more groups selected from the group consisting of. In addition, the same symbols throughout the present specification may have the same meaning unless otherwise specified.

On the other hand, various embodiments of the present invention may be combined with any other embodiments unless clearly indicated to the contrary. Hereinafter, embodiments of the present invention and effects thereof will be described.

The organic light emitting device according to an embodiment of the present invention may be an organic light emitting device including a capping layer. Specifically, the first electrode, the second electrode, one or more organic material layers interposed inside the first and second electrodes, and the first electrode and the second electrode are disposed outside any one or more of the electrode capping of the present invention It may be an organic light emitting device including a capping layer containing a layer compound.

As a specific example of the compound for a capping layer of the present invention, a compound for a capping layer represented by the following Chemical Formula 1 may be mentioned.

<Formula 1>

In Formula 1,

X1 to X7 are each independently C, CR or N, wherein each R is 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, or substituted or unsubstituted C6~ C50 aryl group, or substituted or unsubstituted C2~ It is a C50 heteroaryl group, and a plurality of adjacent Rs may or may not form a ring by bonding with each other,

Ar1 and Ar2 are each independently a substituted or unsubstituted C6~ C50 aryl group, or a substituted or unsubstituted C2~C50 heteroaryl group,

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

In the above, when substituted, the substituent is 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 It may be an 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.

Any one of X1 to X7 is C, and L is directly bonded to C.

The compound of the present invention represented by Formula 1 includes at least one nitrogen (N) in the form of indolizine or imidazole pyridine, etc., but includes a heterobicyclic ring in which nitrogen (N) is necessarily located at a specific position As an arylamine compound, it has a wide bandgap and a high refractive index that is difficult to absorb in the visible light region, and at the same time the absorption wavelength in the ultraviolet region is increased to realize high color purity, high efficiency, and long lifespan organic light emitting device. In addition, by minimizing the bulky characteristic of the terminal end of arylamine, the refractive index is improved because the intermolecular thin film arrangement is excellent, and since it has high Tg and high Td, intermolecular recrystallization is prevented, and it is stable from heat generated when driving an organic light emitting device. By maintaining the thin film and protecting the device from external air and moisture, the stability is improved, so that the external quantum efficiency is increased and the lifespan of the organic light emitting device is significantly improved.

Specific examples of the compound for the capping layer of the present invention include a compound for a capping layer represented by Chemical Formula 1 below, Chemical Formula 2 or Chemical Formula 3 below.

<Formula 2>

<Formula 3>

In Formula 2 and Formula 3,

X1 to X7, Ar2, L, L1, and L2 are the same as defined in Formula 1 above.

Any one of X1 to X7 is C, and L, L1 or L2 is directly bonded to C.

The compound for a capping layer of the present invention represented by Chemical Formula 2 or Chemical Formula 3 includes two or three heterobicyclic rings compared to Chemical Formula 1, thereby achieving a higher refractive index and increasing the absorption wavelength in the ultraviolet region. Stability can be improved from external UV exposure through

In addition, as a specific exemplary compound of the compound for a capping layer of the present invention, the compound for a capping layer represented by Chemical Formula 1 below may be exemplified by Chemical Formula 4 below.

<Formula 4>

In Formula 4,

X1 to X7, L1, L2, Ar1 and Ar2 are the same as defined in Formula 1 above,

R1 is each independently the same as the definition of R in Formula 1,

l is an integer from 0 to 5,

m is each independently an integer from 0 to 4.

Specifically, l may be an integer of 1 or more.

In the compound for a capping layer of the present invention represented by Chemical Formula 4, a heterobicyclic ring is bonded to the amine core (N) as compared to Chemical Formula 1, and is directly bonded or bonded by one or more phenylene groups, thereby absorbing blue region The wavelength may be minimized, and it may be effective in improving the refractive index.

In addition, as a specific exemplary compound of the compound for the capping layer of the present invention, the compound for the capping layer represented by the following Chemical Formula 5 in Chemical Formula 1 may be mentioned.

<Formula 5>

In Formula 5,

X1 to X7, L1, L2, Ar1 and Ar2 are the same as defined in Formula 1 above,

R1 is each independently the same as the definition of R in Formula 1,

l is an integer from 0 to 5,

m is each independently an integer from 0 to 4.

Specifically, l may be an integer of 1 or more.

In the compound for a capping layer of the present invention represented by Formula 5, a heterobicyclic ring is bonded to the amine core (N) as compared to Formula 1, and is bonded directly or by one or more 1,4-phenylene groups, It has a high refractive index and at the same time, it is possible to improve stability from external ultraviolet exposure through an increase in absorption wavelength in the ultraviolet region.

Meanwhile, in Formulas 1 to 5, L, L1 and L2 may each independently include a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, or a combination thereof. Although not limited, at least one of L, L1 and L2 may be a 1,4-phenylene group, and specifically, all of L, L1 and L2 may consist of one or a plurality of 1,4-phenylene groups. In this case, it is possible to maintain a high refractive index, and it can be effective to improve the deposition temperature.

Meanwhile, in Formulas 1 to 5, X1 to X7 may each independently be C or CR. Here, R is the same as defined in Formula 1 above. Specifically, CR may be CH. Through this, the bulky characteristic can be reduced, and long-wavelength absorption can be minimized.

Meanwhile, in Formulas 1 to 5, at least one of X1 to X7 may be N. Through this, a higher refractive index can be realized, and it can be effective to increase the absorption intensity of the ultraviolet region. Specifically, at least one of X1 and X3 may be N. More specifically, X1 may be N.

Also, in Formulas 1 to 5, X2 may be C. That is, by bonding with L, L1 or L2 at the X2 position of the heterobicyclic ring, the refractive index can be increased, and the absorption intensity of the ultraviolet region can be increased.

In addition, in Formulas 1 to 5, Ar1 and Ar2 are each independently and independently phenyl, biphenyl, terphenyl, naphthyl, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, carbazole, phenane It may include trene, triphenylene, or a combination thereof, and in this case, the bulky characteristic of the substituent may be minimized, and the intermolecular thin film arrangement may be excellent to have a high refractive index, and absorption of the ultraviolet region may be increased.

In addition, when Formula 1 is represented by Formula 6, at least one of A, Ar1, and Ar2 may include any one of Formulas A-1 to A-26.

In the following formulas A-1 to A-26, * is a bonding position bonded to L, L1 or L2.

<Formula 6>

In addition, in Formulas 1 to 5, at least one of -L1-Ar1 and -L2-Ar2 is any one selected from the following Formulas B-1 to B-8 or selected from the following Formulas B-1 to B-8 may contain one.

In Formulas B-1 to B-8, q is each independently an integer of 0 to 3, and * is a bonding position bonded to the amine core (N).

By having the structures of Chemical Formulas B-1 to B-8, high refractive index, stability of intermolecular thin film arrangement, increase of absorption intensity in ultraviolet region, and minimization of absorption in blue region can be excellently implemented. Specifically, at least one of -L1-Ar1 and -L2-Ar2 may be represented by Formula B-2 or B-8.

In addition, Chemical Formula 1 may be a compound for a capping layer represented by any one of the following compounds. Since the following compounds are merely examples for explaining the present invention, the present invention is not limited thereto.

An embodiment of the compound for the capping layer of the present invention may be synthesized by an amination reaction, and a schematic synthesis reaction scheme is as follows.

(h = halogen atom)

(h = halogen atom)

According to another embodiment of the present invention, an organic light emitting device including a capping layer, wherein the capping layer includes the above-described compound for a capping layer, is provided.

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

According to one embodiment of the present invention, the organic light emitting device may include a first electrode, a second electrode, and one or more organic material layers interposed inside the first electrode and the second electrode, and the capping layer is the first electrode. One or more of the first electrode and the second electrode may be disposed on the outside of the electrode.

Specifically, the thickness of the capping layer may have a value of 100 to 2000 Å.

In addition, the capping layer may have a refractive index at 450 nm of 2.20 or more, specifically 2.25 or more, more specifically 2.30 or more, and an ultraviolet absorption intensity at 380 nm of 0.7 or more, specifically 0.8 or more.

Here, a side adjacent to the organic material layer interposed between the first electrode and the second electrode among both sides of the first electrode or the second electrode is referred to as an inner side, and a side not adjacent to the organic material layer is referred to as an outer side. That is, when the capping layer is disposed outside the first electrode, the first electrode is interposed between the capping layer and the organic material layer, and when the capping layer is disposed outside the second electrode, the second electrode is interposed between the capping layer and the organic material layer do.

According to one embodiment of the present invention, in the organic light emitting device, one or more various organic material layers may be interposed inside the first electrode and the second electrode, and at least one or more of the first electrode and the second electrode may be disposed on the outside of the electrode. A capping layer may be formed. 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.

In addition, the capping layer may include the compound for the capping layer according to the present invention, and may include the compound for the capping layer according to the present invention alone, include two or more kinds, or include a known compound together.

Meanwhile, the organic material layer may generally include a hole transport layer, a light emitting layer, and an electron transport layer constituting the light emitting part, but may not be limited thereto.

More specifically, the organic light emitting device according to an embodiment of the present invention includes a hole injection layer (HIL), a hole transport layer (HTL), a light emitting layer (HTL) between a first electrode (anode) and a second electrode (cathode) ( EML), an electron transport layer (ETL), an electron injection layer (EIL) may include one or more organic material layers constituting the light emitting portion.

1 is a cross-sectional view schematically showing the configuration of an organic light emitting device according to an embodiment of the present invention. The organic light emitting device according to an embodiment of the present invention may be manufactured as shown in FIG. 1 .

As shown in FIG. 1 , the organic light emitting device includes 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 , and an electron injection layer from the bottom. 600 , the second electrode 2000 , and the capping layer 3000 may be sequentially stacked.

The substrate 100 may be a substrate commonly used in organic light emitting devices, and in particular, a transparent glass substrate or a flexible plastic substrate excellent in mechanical strength, thermal stability, transparency, surface smoothness, handling, and waterproof properties. have.

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

The hole injection layer 200 may be formed by depositing a hole injection layer material on the first electrode 1000 by a method such as a vacuum deposition method, a spin coating method, a casting method, a Langmuir-Blodgett (LB) method, etc. have. 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 properties of the hole injection layer 200, etc. In general, a deposition temperature of 50-500° C., ^{a vacuum degree of 10 -8} to 10 ^-3 torr, a deposition rate of 0.01 to 100 Å/sec, and a layer thickness of 10 Å to 5 μm may be appropriately selected. Meanwhile, a charge generating layer may be additionally deposited on the surface of the hole injection layer 200 if necessary. A conventional material may be used as the material for the charge generation layer, for example, HATCN.

Next, the hole transport layer 300 may be formed by depositing a hole transport layer material on the hole injection layer 200 by a method such as a vacuum deposition method, a spin coating method, a casting method, a LB method, or the like. In the case of forming the hole transport layer 300 by the vacuum deposition method, the deposition conditions vary depending on the compound used, but in general, it is preferable to select within the same range of conditions as those of the hole injection layer 200 . The hole transport layer 300 may be formed using a known compound. The hole transport layer 300 may have one or more layers, and although not shown in FIG. 1 , a light emitting auxiliary layer may be additionally formed on the hole transport layer 300 .

The light emitting layer 400 may be formed by depositing a light emitting layer material on the hole transport layer 300 or the light emitting auxiliary layer by a method such as a vacuum deposition method, a spin coating method, a casting method, or an LB method. In the case of forming the light emitting layer 400 by the vacuum deposition method, the deposition conditions vary depending on the compound used, but in general, it is preferable to select within the same range of conditions as those for the formation of the hole injection layer 200 . As the light emitting layer material, a known compound may be used as a host or a dopant.

On the other hand, when a phosphorescent dopant is used together with the light emitting layer material, a hole blocking material (HBL) is added on the light emitting layer 400 to prevent the triplet excitons or holes from diffusing into the electron transport layer 500 by vacuum deposition or It can be laminated through a spin coating method. In this case, the hole-blocking material that can be used is not particularly limited, and a known material may be arbitrarily selected and used. For example, an oxadiazole derivative, a triazole derivative, a phenanthroline derivative, or a hole-inhibiting material described in Japanese Patent Application Laid-Open No. Hei 11-329734 (A1), etc. are mentioned. Representatively, Balq (bis(8-hydra) Roxy-2-methylquinolinol nato)-aluminum biphenoxide), phenanthrolines-based compounds (eg, UDC's BCP (vasocuproin)), etc. may be used. The light emitting layer 400 of the present invention may include one or more or two or more blue light emitting layers.

The electron transport layer 500 is formed on the light emitting layer 400 , and may be formed by a vacuum deposition method, a spin coating method, a casting method, or the like. The deposition conditions of the electron transport layer 500 vary depending on the compound used, but in general, it is preferable to select the electron transport layer 500 in the same condition range as the formation of the hole injection layer 200 .

The electron injection layer 600 may be formed by depositing an electron injection layer material on the electron transport layer 500 , and may be formed by a vacuum deposition method, a spin coating method, a casting method, or the like.

The organic material layers such as the hole injection layer 200, the hole transport layer 300, the light emitting layer 400, and the electron transport layer 500 of the organic light emitting device may be manufactured using a known material, but is not limited thereto.

The second electrode 2000 is used as an electron injection electrode, and may be formed on the electron injection layer 600 by a method such as a vacuum deposition method or a sputtering method. Various metals may be used as a material of the second electrode 2000 . Specific examples include, but are not limited to, materials such as aluminum, gold, silver, and magnesium.

The organic light emitting device of the present invention has the above-described capping 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), an organic light emitting device having a structure including the second electrode 2000 and the capping layer 3000, as well as an organic light emitting device having a variety of structures are possible. It is also possible to include

On the other hand, the thickness of each organic material layer formed according to the present invention can be adjusted according to the required degree, specifically 1 to 1,000 nm, more specifically, may be 1 to 100 nm.

The capping layer 3000 may be formed on an outer surface on which the hole injection layer 200 is not formed among both sides of the first electrode 1000 . In addition, the second electrode 2000 may be formed on the outer side on which the electron injection layer 600 is not formed among both side surfaces, but is not limited thereto. The capping layer 3000 may be formed by a deposition process, and the capping layer 3000 may have a thickness of 100 to 2,000 Å, more specifically, 300 to 1,000 Å. Through such thickness control, it is possible to prevent a decrease in transmittance of the capping layer 3000 .

In addition, although not shown in FIG. 1 , according to an exemplary embodiment of the present invention, various functions are provided between the capping layer 3000 and the first electrode 1000 or between the capping layer 3000 and the second electrode 2000 . An organic material layer may be additionally formed. Alternatively, an organic material layer having various functions may be additionally formed on the upper portion (outer surface) of the capping layer 3000 , but is not limited thereto.

Hereinafter, an organic light emitting device including a capping layer according to an embodiment of the present invention will be described in detail through Manufacturing Examples and Examples. The following Preparation Examples and Examples only illustrate the present invention, but the scope of the present invention is not limited to the following Preparation Examples and Examples.

production example 1: Synthesis of compound 53

2-(4'-bromo-[1,1'-biphenyl]-4-yl)indolizine 3.0g, bis(4-(naphthalen-2-yl)phenyl)amine 4.0g, t-BuONa 120g in a round bottom flask , Pd ₂ (dba) ₃ 0.3 g, (t-Bu) ₃ P 0.4 ml was dissolved in 110 ml toluene, followed by stirring under reflux. The reaction was confirmed by TLC (Thin Layer Chromatography), and the reaction was terminated after addition of water. The organic layer was extracted with MC (Methylene chloride), filtered under reduced pressure, and recrystallized to obtain compound 53 , 4.0g (yield 68%).

m/z: 688.29 (100.0%), 689.29 (56.7%), 690.29 (15.9%), 691.30 (2.9%)

production example 2: Synthesis of compound 161

Prepared in the same manner as in Preparation Example 1, but 2-(4'-bromo-[1,1'-biphenyl]- instead of 2-(4'-bromo-[1,1'-biphenyl]-4-yl)indolizine Compound 161 was synthesized using 4-yl)imidazo[1,2-a]pyridine. (Yield 65%)

m/z: 689.28 (100.0%), 690.29 (55.6%), 691.29 (15.1%), 692.29 (2.8%), 690.28 (1.1%)

production example 3: Synthesis of compound 168

Prepared in the same manner as in Preparation Example 1, but 2-(4'-bromo-[1,1'-biphenyl]-4-yl)indolizine and bis(4-(naphthalen-2-yl)phenyl)amine instead of 2- Compound 168 was synthesized using (4-bromophenyl)imidazo[1,2-a]pyridine and [1,1':4',1":4'',1'''-quaterphenyl]-4-amine (Yield 64%)

m/z: 705.29 (100.0%), 706.29 (55.9%), 707.30 (14.5%), 708.30 (2.5%), 707.29 (1.0%)

production example 4: Synthesis of compound 170

Prepared in the same manner as in Preparation Example 1, but 2-(4'-bromo-[1,1'-biphenyl]-4-yl)indolizine and bis(4-(naphthalen-2-yl)phenyl)amine instead of 2- Compound 170 was synthesized using (4-bromophenyl)imidazo[1,2-a]pyridine and 4'-(naphthalen-2-yl)-[1,1'-biphenyl]-4-amine. (Yield 66%)

m/z: 679.27 (100.0%), 680.28 (52.3%), 681.28 (13.4%), 682.28 (2.4%), 680.27 (1.8%)

production example 5: Synthesis of compound 178

Prepared in the same manner as in Preparation Example 1, but 2-(4'-bromo-[1,1'-biphenyl]-4-yl)indolizine and bis(4-(naphthalen-2-yl)phenyl)amine instead of 2- Compounds using (4-bromophenyl)imidazo[1,2-a]pyridine and 4'-(imidazo[1,2-a]pyridin-2-yl)-[1,1'-biphenyl]-4-amine 178 was synthesized. (Yield 61%)

m/z: 669.26 (100.0%), 670.27 (49.0%), 671.27 (11.8%), 670.26 (2.6%), 672.27 (2.1%), 671.26 (1.3%) m/z: 711.21 (100.0%), 712.21 (54.5%), 713.21 (15.4%), 713.20 (9.1%), 714.20 (5.0%), 714.22 (2.5%), 712.20 (2.0%), 715.21 (1.4%)

Manufacturing of organic light emitting devices

An organic light emitting device was manufactured according to the structure shown in FIG. 1 . The organic light emitting device includes a substrate 100, an anode (hole injection electrode 1000), a hole injection layer 200, a hole transport layer 300, a light emitting layer 400, an electron transport layer 500, and an electron injection layer 600 from below. ), a cathode (electron injection electrode 2000), and a capping layer 3000 are stacked in this order.

The compounds used in the organic material layer positioned inside the electrode of the organic light emitting device of the present invention are shown in Table 1 below.

Example One

After forming a hole injection layer HI01 600 Å, HATCN 50 Å, and HT01 500 Å as a hole transport layer on an ITO substrate on which a reflective layer containing Ag was formed, the light emitting layer was doped with BH01:BD01 3% to form a film of 250 Å. Next, ET01:Liq(1:1) 300 Å was formed as an electron transport layer, and then LiF 10 Å was deposited to form an electron injection layer. Subsequently, MgAg was deposited to a thickness of 15 nm, and the compound prepared in Preparation Example 1 was deposited to a thickness of 500 Å as a capping layer on the cathode. An organic light emitting device was manufactured by encapsulating this device in a glove box.

Example 2 to Example 5

An organic light emitting diode was prepared in the same manner as in Example 1, except that the capping layer was formed by using the compounds prepared in Preparation Examples 2 to 5, respectively.

comparative example 1 to comparative example 3

An organic light emitting diode formed into a film as a capping layer was manufactured in the same manner as in Example 1, except that Comparative Compound 1 (Ref. 1) to Comparative Compound 3 (Ref. 3) shown in Table 2 below was used.

-

< Experimental example 1> Performance evaluation of organic light emitting devices

Electrons and holes are injected by applying voltage with a Kiethley 2400 source measurement unit, and the luminance when light is emitted is measured using a Konica Minolta spectroradiometer (CS-2000). Thus, the performances of the organic light emitting devices of Examples 1 to 5 and Comparative Examples 1 to 3 were evaluated by measuring the current density and luminance with respect to the applied voltage under atmospheric pressure conditions, and the results are shown in Table 3.

division Op. V mA/cm2 Cd/A CIEx CIEy LT97 Example 1 3.45 10 7.59 0.139 0.044 170 Example 2 3.45 10 7.70 0.140 0.044 178 Example 3 3.46 10 7.74 0.140 0.044 180 Example 4 3.45 10 7.75 0.140 0.043 182 Example 5 3.46 10 7.78 0.140 0.044 185 Comparative Example 1 3.46 10 6.40 0.131 0.056 81 Comparative Example 2 3.46 10 6.65 0.130 0.052 98 Comparative Example 3 3.46 10 6.82 0.133 0.050 103

Comparing Examples of the present invention, compared to Comparative Example 1, the present invention has a high refractive index by minimizing bulky characteristics by a heterobicyclic ring such as imidazopyridine and one arylamine bond, and at the same time absorption in the ultraviolet region It is effective in improving the efficiency and lifespan of an organic light emitting device by increasing the wavelength and high Tg.

In addition, as compared to Comparative Examples 2 and 3, the present invention includes a heterobicyclic ring in which nitrogen (N) is positioned at a specific position, thereby minimizing the bulky properties of the core and increasing the polarization of the molecule, which is an excellent thin film The arrangement can improve the refractive index and form a stable thin film at the same time, so it is possible to realize an organic light emitting device with low driving voltage, high color purity, high efficiency, and long life.

< Experimental example 2> Evaluation of refractive index

Using the compounds 161 and 170 of the present invention prepared above and Comparative Compounds 1 (Ref. , and the refractive index of 450 nm was measured using an ellipsometer device (JAWoollam Co. Inc, M-2000X). The results are summarized in Table 4 below.

@450nm Comparative compound 1 (Ref. 1) Comparative compound 2 (Ref.2) Comparative compound 3 (Ref.3) compound 161 compound 170 refractive index, n 1.99 2.08 2.14 2.33 2.35

As shown in Table 4, it can be seen that compounds 161 and 170 of the present invention exhibit a high refractive index of 2.20 or more, specifically 2.25 or more, more specifically 2.30 or more, at 450 nm.

< Experimental example 3> Evaluation of absorption intensity in the ultraviolet region

In the ultraviolet region, using the compounds 161 and 170 of the present invention prepared previously and Comparative Compounds 1 (Ref. It was manufactured using deposition equipment, and the absorption wavelength within the range of 340 nm to 460 nm was measured using an ellipsometer device (JAWoollam Co. Inc, M-2000X). The result is as shown in FIG. 2 .

The absorption intensity of compounds 161 and 170 of the present invention in the UV absorption region of 380 nm was 0.7 or more, more specifically, 0.8 or more, indicating an increase of 50% or more in absorption intensity, more specifically 60% or more, compared to Comparative Compound 1 (Ref. 1). can be checked

100: substrate
200: hole injection layer
300: hole transport layer
400: light emitting layer
500: electron transport layer
600: electron injection layer
1000: first electrode
2000: second electrode
3000: capping layer

Claims (19)

A compound for a capping layer represented by Formula 1 below:
<Formula 1>

(In Formula 1,
X1 to X7 are each independently C, CR or N, wherein each R is 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, or substituted or unsubstituted C6~ C50 aryl group, or substituted or unsubstituted C2~ It is a C50 heteroaryl group, and a plurality of adjacent Rs may or may not form a ring by bonding with each other,
Ar1 and Ar2 are each independently a substituted or unsubstituted C6~ C50 aryl group, or a substituted or unsubstituted C2~C50 heteroaryl group,
L, L1 and L2 are each independently a direct bond, a substituted or unsubstituted C6-C50 arylene group, or a C2-C50 heteroarylene group).
According to claim 1,
Formula 1 is a compound for a capping layer represented by Formula 2 or Formula 3 below:
<Formula 2>

<Formula 3>

(In Formula 2 and Formula 3,
X1 to X7, Ar2, L, L1, and L2 are the same as defined in Formula 1 above).
According to claim 1,
Formula 1 is a compound for a capping layer represented by Formula 4 below:
<Formula 4>

(In Formula 4,
X1 to X7, L1, L2, Ar1, and Ar2 are the same as defined in Formula 1 above,
R1 is each independently the same as the definition of R in Formula 1,
l is an integer from 0 to 5,
m is each independently an integer from 0 to 4).
According to claim 1,
Formula 1 is a compound for a capping layer represented by Formula 5 below:
<Formula 5>

(In Formula 5,
X1 to X7, L1, L2, Ar1, and Ar2 are the same as defined in Formula 1 above,
R1 is each independently the same as the definition of R in Formula 1,
l is an integer from 0 to 5,
m is each independently an integer from 0 to 4).
According to claim 1,
wherein X1 to X7 are each independently C or CR; a compound for a capping layer.
6. The method of claim 5,
In CR, R is hydrogen. A compound for a capping layer.
According to claim 1,
wherein at least one of X1 to X7 is N. A compound for a capping layer.
According to claim 1,
wherein at least one of X1 and X3 is N. A compound for a capping layer.
According to claim 1,
wherein X2 is C; a compound for a capping layer.
According to claim 1,
Wherein L, L1 and L2 are each independently a phenylene group, a biphenylene group, a terphenylene group, a naphthylene group, or a compound for a capping layer comprising a combination thereof.
The method of claim 1,
Ar1 and Ar2 each independently include phenyl, biphenyl, terphenyl, naphthyl, benzofuran, benzothiophene, dibenzofuran, dibenzothiophene, carbazole, phenanthrene, triphenylene, or a combination thereof compound for a capping layer.
According to claim 1,
When Formula 1 is represented by Formula 6, at least one of A, Ar1, and Ar2 is a compound for a capping layer comprising any one of Formulas A-1 to A-26:
<Formula 6>

.
According to claim 1,
At least one of -L1-Ar1 and -L2-Ar2 is selected from the following Chemical Formulas B-1 to B-8 or a compound for a capping layer comprising any one selected from the following Chemical Formulas B-1 to B-8:

(In the formulas B-1 to B-8,
q is each independently an integer from 0 to 3).
14. The method of claim 13,
At least one of -L1-Ar1 and -L2-Ar2 is a compound for a capping layer of Formula B-2 or B-8.
The method of claim 1,
Formula 1 is a compound for a capping layer, which is any one of the following compounds:

.
An organic light-emitting device comprising a capping layer containing the compound for a capping layer according to any one of claims 1 to 15.
17. The method of claim 16,
The organic light emitting device may include a first electrode and a second electrode;
Further comprising one or more organic material layers interposed inside the first electrode and the second electrode,
The capping layer is an organic light emitting device disposed outside any one or more of the first electrode and the second electrode.
17. The method of claim 16,
The thickness of the capping layer is 100 to 2000 Å of the organic light emitting device.
17. The method of claim 16,
The capping layer is an organic light emitting diode having a refractive index of 2.20 or more at 450 nm.

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