KR102149077B1 - Organic light emitting device - Google Patents

Abstract

The present specification relates to an organic light emitting device.

Description

Organic light emitting device {ORGANIC LIGHT EMITTING DEVICE}

The present specification relates to an organic light emitting device.

The organic light emitting device has a structure in which an organic thin film is disposed between two electrodes. When a voltage is applied to the organic light-emitting device having such a structure, electrons and electrons injected from the two electrodes are combined in the organic thin film to form a pair and then emit light while disappearing. The organic thin film may be composed of a single layer or multiple layers as necessary.

As materials used in organic light-emitting devices, pure organic materials or complex compounds in which organic materials and metals form a complex occupy most of them, and depending on the purpose, hole injection materials, hole transport materials, light-emitting materials, electron transport materials, electron injection materials, etc. It can be classified as Here, as the hole injection material or the hole transport material, an organic material having a p-type property, that is, an organic material that is easily oxidized and has an electrochemically stable state upon oxidation is mainly used. Meanwhile, as an electron injection material or an electron transport material, an organic material having an n-type property, that is, an organic material that is easily reduced and has an electrochemically stable state upon reduction is mainly used. As the light-emitting layer material, a material having both p-type and n-type properties, that is, a material that is stable in both oxidation and reduction states, is preferable, and excitons generated by recombination of holes and electrons in the emission layer are formed. A material having high luminous efficiency that converts it to light when it is formed is preferable.

In order to improve the performance, life, or efficiency of an organic light emitting device, the development of a material for an organic thin film is continuously required.

Japanese Patent Laid-Open Publication No. 2015-221780

An object of the present specification is to provide an organic light emitting device having high luminous efficiency and/or a low driving voltage and a long lifespan.

An exemplary embodiment of the present specification is an anode; A cathode provided to face the anode; And In the organic light emitting device comprising an organic material layer including a light emitting layer provided between the anode and the cathode,

The emission layer provides an organic light-emitting device comprising a compound represented by Formula 1 and a phosphorescent dopant.

[Formula 1]

In Formula 1,

X1 to X5 are the same as or different from each other, and each independently a substituted or unsubstituted aryl group; Or a substituted or unsubstituted heteroaryl group.

Embodiments of the present invention provide an organic light-emitting device having improved efficiency, low driving voltage and/or improved lifetime characteristics.

1 shows an organic light-emitting device in which a substrate 1, an anode 2, a hole injection layer 5, a hole transport layer 6, a light emitting layer 3, an electron transport layer 7 and a cathode 4 are sequentially stacked. It shows an example.
2 is a diagram showing intensity-wavelength values according to Examples and Comparative Examples.
3 is a diagram showing luminance-time values according to Examples and Comparative Examples.

Hereinafter, the present specification will be described in more detail.

In the present invention, by including a thermally activated delayed fluorescent dopant and a phosphorescent dopant in the light emitting layer of the organic light emitting device, it is possible to increase the lifetime of the organic light emitting device.

Examples of the substituent in the present specification are described below, but are not limited thereto.

The term "substituted" means that the hydrogen atom bonded to the carbon atom of the compound is replaced with another substituent, and the position to be substituted is not limited as long as the position where the hydrogen atom is substituted, that is, the position where the substituent can be substituted, and if two or more are substituted , Two or more substituents may be the same or different from each other.

In the present specification, the term “substituted or unsubstituted” refers to deuterium; Halogen group; Cyano group; Silyl group; Alkyl group; Cycloalkyl group; Aryl group; And it is substituted with one or two or more substituents selected from the group consisting of a heteroaryl group, two or more of the substituents exemplified above are substituted with a connected substituent, or does not have any substituents. For example, the “substituent to which two or more substituents are connected” may be a biphenyl group. That is, the biphenyl group may be an aryl group, or may be interpreted as a substituent to which two phenyl groups are connected.

In the present specification, examples of the halogen group include fluorine (F), chlorine (Cl), bromine (Br), or iodine (I).

In the present specification, the alkyl group may be a linear or branched chain, and the number of carbon atoms is not particularly limited, but is preferably 1 to 60. According to an exemplary embodiment, the number of carbon atoms in the alkyl group is 1 to 40. According to another exemplary embodiment, the alkyl group has 1 to 20 carbon atoms. Specific examples include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, iso Pentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl , 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethylpropyl, 1,1-dimethylpropyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl, and the like, but are not limited thereto.

In the present specification, the cycloalkyl group is not particularly limited, but preferably has 3 to 60 carbon atoms, and according to an exemplary embodiment, the cycloalkyl group has 3 to 40 carbon atoms. According to another exemplary embodiment, the number of carbon atoms of the cycloalkyl group is 3 to 20. Specifically, cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3, 4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, and the like, but are not limited thereto.

In the present specification, the silyl group is specifically trimethylsilyl group, triethylsilyl group, t-butyldimethylsilyl group, vinyldimethylsilyl group, propyldimethylsilyl group, triphenylsilyl group, diphenylsilyl group, phenylsilyl group, etc. However, it is not limited thereto.

In the present specification, when the aryl group is a monocyclic aryl group, the number of carbon atoms is not particularly limited, but it is preferably 6 to 30 carbon atoms. Specifically, the monocyclic aryl group may be a phenyl group, a biphenyl group, or a terphenyl group, but is not limited thereto.

When the aryl group is a polycyclic aryl group, the number of carbon atoms is not particularly limited. It is preferably 10 to 24 carbon atoms. Specifically, the polycyclic aryl group may be a naphthyl group, an anthracene group, a phenanthrene group, a pyrenyl group, a perylenyl group, a chrysenyl group, a fluorenyl group, and the like, but is not limited thereto.

In the present specification, the fluorenyl group may be substituted, and adjacent substituents may be bonded to each other to form a ring.

(9,9-디메틸플루오레닐기),

(9-메틸-9-페닐플루오레닐기),

(9,9-디페닐플루오레닐기),

,

,

등이 있으나, 이에 한정되는 것은 아니다.When the fluorenyl group is substituted,

(9,9-dimethylfluorenyl group),

(9-methyl-9-phenylfluorenyl group),

(9,9-diphenylfluorenyl group),

,

,

And the like, but are not limited thereto.

In the present specification, the heteroaryl group includes one or more of N, O, S, Si, and Se as a heteroatom, and the number of carbons is not particularly limited, but it is preferably 2 to 60 carbon atoms. According to an exemplary embodiment, the heteroaryl group has 2 to 30 carbon atoms. According to another exemplary embodiment, the heteroaryl group has 2 to 20 carbon atoms. Examples of heteroaryl groups include thiophene group, furan group, pyrrole group, imidazole group, thiazole group, oxazole group, oxadiazole group, triazole group, pyridyl group, bipyridyl group, pyrimidyl group, triazine group, triazole group, Acridyl group, pyridazine group, pyrazinyl group, quinolinyl group, quinazoline group, quinoxalinyl group, phthalazinyl group, pyrido pyrimidinyl group, pyrido pyrazinyl group, pyrazino pyrazinyl group, isoquinoline group , Indole group, carbazole group, benzoxazole group, benzimidazole group, benzothiazole group, benzocarbazole group, benzothiophene group, dibenzothiophene group, dibenzofuran group, benzofuranyl group, phenanthroline group , Thiazolyl group, isoxazolyl group, oxadiazolyl group, thiadiazolyl group, and benzothiazolyl group, but are not limited thereto.

In the exemplary embodiment of the present specification, X1 to X5 are the same as or different from each other, and each independently a substituted or unsubstituted aryl group having 6 to 30 carbon atoms; Or a substituted or unsubstituted C2 to C30 heteroaryl group.

According to an exemplary embodiment of the present specification, X1 to X5 are the same as or different from each other, and each independently a substituted or unsubstituted phenyl group; A substituted or unsubstituted biphenyl group; A substituted or unsubstituted fluorene group; A substituted or unsubstituted dibenzofuran group; A substituted or unsubstituted dibenzothiophene group; Or a substituted or unsubstituted carbazole group.

According to another exemplary embodiment, the X1 to X5 are the same as or different from each other, and each independently a phenyl group; Biphenyl group; Fluorene group; Dibenzofuran group; Dibenzothiophene group; Or carbazole group.

According to another exemplary embodiment, X1 to X5 are carbazole groups.

According to an exemplary embodiment of the present specification, the compound represented by Formula 1 may have the following structure.

[5CzCN]

The compound represented by Formula 1 may be prepared by the preparation example described later.

In the present specification, when a member is positioned “on” another member, this includes not only a case where a member is in contact with another member, but also a case where another member exists between the two members.

In the present specification, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated.

The organic material layer of the organic light emitting device of the present application may have a single-layer structure, but may have a multilayer structure in which two or more organic material layers are stacked. For example, as a representative example of the organic light emitting device of the present invention, the organic light emitting device may have a structure including a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, etc. as an organic material layer. However, the structure of the organic light emitting device is not limited thereto and may include a smaller number of organic material layers.

In the exemplary embodiment of the present specification, the organic light emitting device may be a normal type organic light emitting device in which an anode, a light emitting layer, and a cathode are sequentially stacked on a substrate.

In another exemplary embodiment, the organic light emitting device may be an organic light emitting device of an inverted type in which a cathode, a light emitting layer, and an anode are sequentially stacked on a substrate.

For example, the structure of the organic light emitting device according to the exemplary embodiment of the present application is illustrated in FIG. 1.

1 shows an organic light-emitting device in which a substrate 1, an anode 2, a hole injection layer 5, a hole transport layer 6, a light emitting layer 3, an electron transport layer 7 and a cathode 4 are sequentially stacked. The structure is illustrated. In such a structure, the compound represented by Formula 1 and the phosphorescent dopant may be included in the emission layer. The emission layer may emit blue light.

In the exemplary embodiment of the present specification, the phosphorescent dopant may be represented by LL'L”M, and L, L', and L” denote a 2-dentate ligand, and M denotes a metal.

In addition, the L, L'and L” may be the same as or different from each other, and M is coordinated with the sp ² hybrid carbon and hetero atom of the ligand, preferably, M is a third row transition metal, most preferably For example, it is Ir or Pt.

In another exemplary embodiment, the phosphorescent dopant may be an iridium-based complex compound.

According to the exemplary embodiment of the present specification, the phosphorescent dopant may be any one of the following structures, but is not limited thereto.

In the exemplary embodiment of the present specification, the content of the compound represented by Formula 1 is greater than the content of the phosphorescent dopant.

In the exemplary embodiment of the present specification, the emission layer includes a host, includes a compound represented by Formula 1 as a dopant, and further includes the phosphorescent dopant. The content of the compound represented by Formula 1 may be 0.01 to 50 parts by weight based on 100 parts by weight of the host, and the content of the phosphorescent dopant may be 0.01 to 5 parts by weight.

When the compound represented by Formula 1 is included as a dopant, and an emission layer further including the phosphorescent dopant is included, an organic light emitting device having high efficiency and a long lifespan can be manufactured.

According to an exemplary embodiment of the present specification, a host is included as a material of the light emitting layer, a compound represented by Formula 1 is doped with 1 to 20 wt%, and a phosphorescent dopant is doped with 0.1 to 5 wt%, more preferably 0.1 to 3 wt% can do.

The compound of Formula 1 may be used as a thermally activated delayed fluorescence dopant (TADF). The thermally activated delayed fluorescence refers to a phenomenon in which an inverse interphase transition is induced from a triplet excited state to a singlet excited state by thermal energy, thereby causing fluorescence emission.

5CzCN, a compound represented by Chemical Formula 1, has a singlet energy of 2.95 eV, a triplet energy of 2.79 eV, a HOMO energy level of -6.29 eV, and a LUMO energy level of -3.44 eV. Is as follows.

[5CzCN]

The organic light-emitting device of the present application may be manufactured by materials and methods known in the art, except that the light-emitting layer includes Chemical Formula 1 and a phosphorescent dopant of the present application.

For example, the organic light-emitting device of the present application may be manufactured by sequentially laminating an anode, an organic material layer, and a cathode on a substrate. At this time, using a PVD (Physical Vapor Deposition) method such as sputtering or e-beam evaporation, the anode is formed by depositing a metal or a conductive metal oxide or an alloy thereof on the substrate. And, after forming an organic material layer including a hole injection layer, a hole transport layer, a light emitting layer and an electron transport layer thereon, it can be produced by depositing a material that can be used as a cathode thereon. In addition to this method, an organic light-emitting device can be manufactured by sequentially depositing a cathode material, an organic material layer, and an anode material on a substrate.

In addition, when manufacturing the organic light emitting device, a light emitting layer may be formed by a solution coating method as well as a vacuum deposition method. Here, the solution coating method refers to spin coating, dip coating, doctor blading, inkjet printing, screen printing, spray method, roll coating, etc., but is not limited thereto.

As the anode material, a material having a large work function is preferred so that holes can be smoothly injected into the organic material layer. Specific examples of the anode material that can be used in the present invention include metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; Metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); A combination of a metal and an oxide such as ZnO:Al or SnO ₂ :Sb; Poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene] (PEDOT), conductive polymers such as polypyrrole and polyaniline, and the like, but are not limited thereto.

The cathode material is generally preferably a material having a small work function to facilitate electron injection into the organic material layer. Specific examples of the cathode material include metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin, and lead, or alloys thereof; There are multi-layered materials such as LiF/Al or LiO ₂ /Al, but are not limited thereto.

The hole injection layer is a layer that injects holes from an electrode, and has the ability to transport holes as a hole injection material, and thus has a hole injection effect at the anode, an excellent hole injection effect for the light emitting layer or the light emitting material, and is generated from the light emitting layer. A compound that prevents the movement of excitons to the electron injection layer or the electron injection material and has excellent ability to form a thin film is preferable. It is preferable that the HOMO (highest occupied molecular orbital) of the hole injection material is between the work function of the anode material and the HOMO of the surrounding organic material layer. Specific examples of hole injection materials include metal porphyrin, oligothiophene, arylamine-based organic substances, hexanitrile hexaazatriphenylene-based organic substances, quinacridone-based organic substances, and perylene-based organic substances. Organic substances, anthraquinone, polyaniline, and polythiophene-based conductive polymers, etc., but are not limited thereto.

The hole transport layer is a layer that receives holes from the hole injection layer and transports holes to the emission layer.The hole transport material is a material capable of transporting holes from the anode or the hole injection layer to the emission layer, and has high mobility for holes. The material is suitable. Specific examples include an arylamine-based organic material, a conductive polymer, and a block copolymer including a conjugated portion and a non-conjugated portion, but are not limited thereto.

Examples of the host material for the light emitting layer include a condensed aromatic ring derivative or a heterocyclic compound. Specifically, condensed aromatic ring derivatives include anthracene derivatives, pyrene derivatives, naphthalene derivatives, pentacene derivatives, phenanthrene compounds, and fluoranthene compounds, and heterocycle-containing compounds include carbazole derivatives, dibenzofuran derivatives, ladder type Furan compounds, pyrimidine derivatives, and the like, but are not limited thereto.

The electron transport layer is a layer that receives electrons from the electron injection layer and transports electrons to the emission layer.As an electron transport material, a material capable of receiving electrons from the cathode and transferring them to the emission layer, and a material having high mobility for electrons is suitable. Do. Specific examples include the Al complex of 8-hydroxyquinoline; Complexes including Alq3; Organic radical compounds; Hydroxyflavone-metal complexes and the like, but are not limited thereto. The electron transport layer can be used with any desired cathode material as used according to the prior art. In particular, examples of suitable cathode materials are conventional materials that have a low work function and are followed by an aluminum layer or a silver layer. Specifically, they are cesium, barium, calcium, ytterbium and samarium, and in each case an aluminum layer or a silver layer follows.

The electron injection layer is a layer that injects electrons from the electrode, has the ability to transport electrons, has an electron injection effect from the cathode, has an excellent electron injection effect on the light emitting layer or light emitting material, and injects holes of excitons generated in the light emitting layer A compound that prevents migration to the layer and has excellent thin film formation ability is preferable. Specifically, fluorenone, anthraquinodimethane, diphenoquinone, thiopyran dioxide, oxazole, oxadiazole, triazole, imidazole, perylenetetracarboxylic acid, preorenylidene methane, anthrone, and their derivatives, metals Complex compounds and nitrogen-containing 5-membered ring derivatives, but are not limited thereto.

Examples of the metal complex compound include lithium 8-hydroxyquinolinato, bis(8-hydroxyquinolinato)zinc, bis(8-hydroxyquinolinato)copper, bis(8-hydroxyquinolinato)manganese, Tris(8-hydroxyquinolinato)aluminum, tris(2-methyl-8-hydroxyquinolinato)aluminum, tris(8-hydroxyquinolinato)gallium, bis(10-hydroxybenzo[h] Quinolinato)beryllium, bis(10-hydroxybenzo[h]quinolinato)zinc, bis(2-methyl-8-quinolinato)chlorogallium, bis(2-methyl-8-quinolinato)( o-cresolato)gallium, bis(2-methyl-8-quinolinato)(1-naphtholato)aluminum, bis(2-methyl-8-quinolinato)(2-naphtholato)gallium, etc. It is not limited to this.

The hole blocking layer is a layer that prevents holes from reaching the cathode, and may be generally formed under the same conditions as the hole injection layer. Specifically, there are oxadiazole derivatives, triazole derivatives, phenanthroline derivatives, BCP, aluminum complexes, etc., but are not limited thereto.

The organic light emitting device according to the present specification may be a top emission type, a bottom emission type, or a double-sided emission type depending on the material used.

< Example >

The compounds used in Examples 1 to 3 and Comparative Example 1 are as follows.

Example One.

A transparent electrode (Indium Tin Oxide) as a hole injection electrode was deposited on a glass substrate with a thickness of 150 nm, and oxygen plasma treatment was performed at 150w at 50mtorr pressure for 130sec.

The hole injection material cp1 was 60 nm, the hole transport materials cp2 and cp3 were used as 20 nm and 10 nm, respectively, and the host was used as cp3 as the light emitting layer material.The light emitting layer material was doped with 15 wt% of cp4, a deteriorating delayed fluorescent material, and a phosphorescent dopant Phosphorus cp5 was doped with 0.3wt% to make the thickness of the light emitting layer 30 nm, the electron transport layer materials cp6 and cp7 were deposited to a thickness of 5 nm and 30 nm, respectively, and the electron injection layer material LiF was deposited with a 1.5 nm electron injection electrode and Al 200 nm.

Current and voltage were applied to an organic light emitting device made of 0wt% to 1wt% of cp6 using a Keithley 2635A System Source Meter, and the luminance and PL spectrum according to the current and voltage were measured using a CS-2000 Spectroradiometer, and the lifespan was measured by M60000 OLED. It was measured with a lifetime tester (M6000 OLED Lifetime Tester). The lifetime was shown for 65 hours until the luminance decreased by 50% at 1000 cd/m ² .

Example 2.

In Example 1, an organic light-emitting device was manufactured in the same manner as in Example 1, except that cp5, which is a phosphorescent dopant Ir(dbi) ₃ , was doped with 0.5 wt% instead of 0.3 wt%. As a result of the lifetime measurement, the lifetime was 71 hours until the luminance decreased by 50% at 1000 cd/m ² .

Example 3.

In Example 1, an organic light-emitting device was manufactured in the same manner as in Example 1, except that cp5, which is a phosphorescent dopant Ir(dbi) ₃ , was doped with 1 wt% instead of 0.3 wt%. As a result of the lifetime measurement, the lifetime was shown for 60 hours until the luminance decreased by 50% at 1000 cd/m ² .

< Comparative example >

Comparative example One.

In Example 1, an organic light-emitting device was manufactured in the same manner as in Example 1, except that cp5, which is a phosphorescent dopant Ir (dbi) ₃ , was doped with 0 wt% instead of 0.3 wt%. As a result of the lifetime measurement, the lifetime was 33 hours until the luminance decreased by 50% at 1000 cd/m ² .

The current intensity-wavelength and luminance-time values of the organic light-emitting devices manufactured in Examples 1 to 3 and Comparative Example 1 are shown in FIGS. 2 and 3, and Comparative Example 1 Is denoted by ref.

2 and 3, it can be seen that the strength (intensity) and life characteristics of the organic light-emitting device manufactured in Examples 1 to 3 are superior to that of the organic light-emitting device manufactured in Comparative Example 1.

1: substrate
2: anode
3: light emitting layer
4: cathode
5: hole injection layer
6: hole transport layer
7: electron transport layer

Claims (5)

Anode; A cathode provided to face the anode; And In the organic light emitting device comprising an organic material layer including a light emitting layer provided between the anode and the cathode,
The light emitting layer is an organic light emitting device comprising a host, a compound represented by the following Formula 1, and a phosphorescent dopant:
[Formula 1]

In Formula 1,
X1 to X5 are the same as or different from each other, and each independently a substituted or unsubstituted carbazole group. delete The method according to claim 1,
The organic light-emitting device of the X1 to X5 is a carbazole group. The method according to claim 1,
The phosphorescent dopant is an organic light emitting device that is an iridium-based complex compound. The method according to claim 1,
An organic light-emitting device in which the content of the compound represented by Formula 1 is greater than that of the phosphorescent dopant.

Images