WO2008082178A1

WO2008082178A1 - Diaryl trianthracene derivatives and organic light emitting layer or diode comprising the same

Info

Publication number: WO2008082178A1
Application number: PCT/KR2007/006932
Authority: WO
Inventors: Jin-Seok Hong; Tae-Hyung Kim; Mi-Jeong Hwang; Sang-Hoon Lee; Kyoung-Soo Kim
Original assignee: Doosan Corp
Current assignee: Doosan Corp
Priority date: 2006-12-29
Filing date: 2007-12-28
Publication date: 2008-07-10
Anticipated expiration: 2009-06-29
Also published as: KR100868303B1; KR20070101754A

Abstract

Disclosed is a diaryl trianthracene compound represented by Formula 1, with two aryl groups disposed at specific positions, and an organic electroluminescence layer or device comprising the same, which can significantly improve the lifetime of a device, the light-emitting efficiency, and the driving capability with a low voltage.

Description

[DESCRIPTION]

[invention Title]

DIARYL TRIANTHRACENE DERIVATIVES AND ORGANIC LIGHT EMITTING LAYER OR DIODE COMPRISING THE SAME [Technical Field]

The present invention relates to a diaryl trianthracene compound represented by Formula 1, with two aryl groups disposed at specific positions, and an organic electroluminescence layer or device comprising the same, which can significantly improve the lifetime of a device, the light- emitting efficiency, and the driving capability with a low voltage . [Background Art]

An organic electroluminescence (hereinafter, referred to as "EL") device is a self-emitting device, and herein, when voltage is applied, a fluorescent material emits light by recombination energy of a hole injected from an anode, and an electron injected from a cathode.

It is known that the device structure of an organic EL device includes a two-layered type having a hole transport (injection) layer and an electron transport/light emitting layer, or a three-layered type having a hole transport (injection) layer, a light emitting layer, and an electron transport (injection) layer, etc. In the field of a device including such a layered structure, research on a device structure for improving the recombination efficiency of an injected hole and an injected electron, and a method of manufacturing the same has been performed. Such a layered structure has an advantage in that it is possible to improve the efficiency of injecting a hole to a light emitting layer, to improve the efficiency of generating an exciton (which is generated through recombination) by blocking an electron injected from a cathode, to keep the generated exciton within a light emitting layer, etc.

Since a low-voltage driven organic EL device using a layered device based on vacuum deposition was reported by CW. Tang, et al. of the Eastman Kodak Company in 1987, research on an organic EL device using an organic material as a constituent material has been actively performed. Tang et al. used tris (8-hydroxyquinolinol aluminum) for a light emitting layer, and triphenyldiamine derivative for a hole transport layer. In an organic EL device, when forward voltage is applied to the device, a hole and an electron are injected from an anode and a cathode, respectively. Next, the hole and the electron are recombined in a light emitting layer, and thereby form an exciton, that is, a couple of the electron and the hole. Then, the exciton having a structure where a pi-electron of a molecule is in an excited state is back in a ground state, thereby converting corresponding energy into light.

Recently, in order to improve the color purity and efficiency of emitted light, a method of doping a small amount of fluorescent dye or phosphorescent dye on a light emitting layer where an exciton is formed has been used. The principle used for the method is based on that when a small amount of fluorescent/phosphorescent dye (hereinafter, referred to as "dopant") having a smaller energy band gap than that of a molecule forming a light emitting layer is mixed to a light emitting layer, an exciton generated from the light emitting layer is transferred to the dopant and emits light with high efficiency.

Conventionally, various green-light emitting materials, such as 8-hydroquinoline aluminum salt, etc. have been used as hosts. However, anthracene-based aromatic amine derivative compounds (including the above compound) , which are provided in the prior art, cannot sufficiently solve the problem of crystallization. In other words, in using the above compounds for a long time, the lifetime of a device and the light- emitting efficiency must be improved, and also, an electroluminescent material capable of being driven even at a low voltage is required to be developed. [Disclosure] [Technical Problem]

Therefore, the present invention has been made in view of the above-mentioned problems, and the present invention provides a diaryl trianthracene derivative, which significantly improves the lifetime of a material, the light- emitting efficiency, and the driving capability with a low voltage, by introducing two aryl groups at specific positions, and an organic electroluminescence (EL) layer or device comprising the same.

In preparing an organic EL device of a multi-layered structure where at least one organic thin film layer including an organic compound is included between a substrate and an anode layer/a cathode layer, the provided new material is used as a new light-emitting material which significantly improves the lifetime of a device, and the light-emitting efficiency. [Technical Solution]

According to an aspect of the present invention, there is provided a diaryl trianthracene derivative, and more particularly a diaryl trianthracene derivative represented by Formula 1.

[Formula 1]

In the formula, Ari and Ar₂ are the same or different from each other, and each of Ari and Ar₂ is independently an aryl group or an aromatic ring selected from the group including benzene, naphthalene, biphenyl, and anthracene; and Ri ~ R₂₄ are the same or different from each other, and each of Ri ~ R₂₄ is independently selected from the group including hydrogen, a halogen group, a substituted or unsubstituted Ci-C₃₀ alkyl group, a substituted or unsubstituted Ci-C₃₀ alkenyl group, a substituted or unsubstituted C₅~C₃o aryl group, a substituted or unsubstituted C₅-C₃₀ arylalkyl group, a substituted or unsubstituted C₅-C₃₀ aryloxy group, a substituted or unsubstituted C₅-C₃₀ heteroaryl group, a substituted or unsubstituted C₅-Ci_O cycloalkyl group, and a substituted or unsubstituted C5-C₁0 heterocycloalky L group, or form a condensed ring between adjacent substituents.

In a trianthracene, a main frame for a diaryl trianthracene derivative according to the present invention, Ari and Ar₂, which is an aryl group or an aromatic ring, may be bonded at various positions. However, compared to when an aryl group is located at another location (especially, at R5 and/or R17) , when Ar_x and Ar₂ are located at the positions in a compound represented by Formula 1, a carbon-carbon rotation is not easy, and additionally, anthracenes are likely to be further from a plane by a large steric hindrance. Therefore, there is little possibility that an intermolecular excimer is formed or concentration quenching occurs, and thus, a final organic EL device is very good in improving the lifetime of a device, the light-emitting efficiency, and the driving capability with a low voltage. In the present invention, an alkyl group includes a linear alkyl group, a branched alkyl group, and a cyclic alkyl group, and representative examples of the substituted or unsubstituted Ci-C₃₀ alkyl group include, but are not limited to, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, a tert- butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, etc. In the present invention, representative examples of the substituted or unsubstituted Ci-C_3O alkenyl group include, but are not limited to, diphenylethene, phenyl naphthyl ethene, dinaphthyl ethene, etc.

In the present invention, representative examples of the substituted or unsubstituted C₅-C₃₀ aryl group include, but are not limited to, a phenyl group, a 2-methylphenyl group, a 3- methylphenyl group, a 4-methylphenyl group, a 4-ethylphenyl group, a biphenyl group, a 4-methylbiphenyl group, a 4- ethylbiphenyl group, a 4-cyclohexylbiphenyl group, a terphenyl group, a 3, 5-dichlorophenyl group, a naphthyl group, a 5- methylnaphthyl group, an anthryl group, a pyrenyl group, etc.

Representative examples of the substituted or unsubstituted C₅-C₃₀ arylalkyl group include, but are not limited to, a benzyl group, an α-methylbenzyl group, an α- ethylbenzyl group, an α,α-dimethyl benzyl group, a 4- methylbenzyl group, a 4-ethylbenzyl group, a 2-tert-butyl benzyl group, a 4-n-octyl benzyL group, a naphthylmethyl group, a diphenylmethyl group, etc.

In the present invention, representative examples of the aryloxyl group include, but are not limited to, a phenoxyl group, a naphthyloxyl group, an anthryloxyl group, a pyrenyloxyl group, a fluorantenyloxyl group, a chrysenyloxyl group, a perylenyloxyl group, etc.

In the present invention, representative examples of the substituted or unsubstituted C₅-C_3O heteroaryl group include, but are not limited to, pyridine, quinoline, isoquinoline, phenylisoquinoline, etc.

In the present invention, representative examples of the substituted or unsubstituted C₅-Ci₀ cycloalkyl group include, but are not limited to, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a norbornenyl group, an adamantyl group, etc. In the present invention, representative examples of the substituted or unsubstituted C₅-Ci₀ heterocycloalkyl group include, but are not limited to, a pyridyl group, a tiethyl group, a furyl group, a quinolyl group, a carbazolyl group, etc. In the present invention, representative examples of the substituted functional group include, but are not limited to: halogen atoms such as a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.; alkyl groups such as a methyl group, an ethyl group, an n-propyl group, and an isopropyl group; alkoxyl groups such as a methoxyl group and an ethoxyl group; aryloxy groups such as a phenoxyl group; arylalkyl groups such as a benzyl group, a phenethyl group, and a phenylpropyl group; a nitro group; a cyano group; substituted amino groups such as a dimethylamino group, a dibenzylamino group, a diphenylamino group, and a porpholino group; aryl groups such as a phenyl group, a tolyl group, a biphenyl group, a naphthyl group, an anthryl group, and a pyrenyl group; and heterocyclic groups such as a pyridyl group, a tiethyl group, a furyl group, a quinolyl group, and a carbazolyl group.

According to a preferred embodiment, the present invention relates to a diaryl trianthracene derivative selected from the group including compounds represented by Formulas 2~5. [Formula 2]

\Formula 3]

[Formula 4]

^'Formula 5]

According to another aspect of the present invention, there is provided an organic electroluminescence (EL) layer comprising the diaryl trianthracene derivative according to the present invention, and an organic EL device comprising the same diaryl trianthracene derivative.

Although in the preferred embodiment of the present invention, preparation/experimental examples of a diaryl trianthracene derivative according to Formulas 2 and 3 is described for illustrative purposes, those skilled in the art can easily obtain a diaryl trianthracene derivative according to the present invention, besides the Formulas 2 and 3, based on the following Examples and techniques in the art, and can prepare a device comprising the same. Also, in the present invention, the use of the compound represented by Formula 1 prevents the crystallization of anthracene, which is caused by a stereostructure, and thus improves the lifetime of a device, the light-emitting efficiency, and the heat-resistance of an organic EL device even at a high temperature. Therefore, although the lifetime of a device, and the light-emitting efficiency of all compounds according to the present invention is not described in embodiments of the present invention, those skilled in the art will appreciate that it is possible to improve the lifetime of a device and the light-emitting efficiency as long as the compound represented by Formula 1 is used.

In the present invention, representative examples of a compound used for a hole injection layer material include, but are not limited to, a DS-205 developed by this company. In the present invention, representative examples of a compound used for a forming material of a hole transport layer include, but are not limited to, N, N' -diphenyl-N-N-bis (1- naphthyl) -1, 1 ' -biphenyl-4, 4 ' -diamine compound described in Table 1. In the present invention, representative examples of a compound used for a forming material of an electron transport layer include, but are not limited to, 8-hydroquinoline aluminum salt compound described in Table 1.

In the present invention, representative examples of a compound used for a green-light emitting dopant, and a blue- light emitting dopant include, but are not limited to, compounds described in Table 1, which are registered in US Patent Application Publication No. 2005/0260442 and in European patent No. EP 1314715. [Table l]

[Table 2]

[Best Mode]

Reference will now be made in detail to the preferred embodiments of the present invention. However, the following examples are illustrative only, and the scope of the present invention is not limited thereto. Preparation Example 1: preparation of a compound a As described in following Reaction Scheme 1, 9- bromoanthracene (29.6g, 114.9 mmol) was dissolved in purified THF (25OmL) under a nitrogen atmosphere, was cooled to -78 ^°C, and then, n-butyllithium hexane solution (82mL, 1.6 M) was slowly added to the resultant mixture. After agitation for 1 hour at the same temperature, 2- bromoanthraquinone (15.Og, 41.0 mmol) was added to the reaction product at the same temperature. Then, after a cooling container was removed, the reaction product was agitated for 5 hours at room temperature. Next, after_the reaction solution was removed, the resultant product was subjected to solvent extraction using water and dichloromethane, and then the used solvent was removed. The resultant product was sufficiently cleaned by n-hexane, and was vacuum-dried to obtain a compound a of light brown solid (30.5g, yield 91%) .

[Reaction Scheme 1]

bromotrianthracene

As described in following Reaction Scheme 2, the compound a (20.Og, 31.9 mmol) prepared by Preparation Example 1, and a mixture of potassium iodide (51. βg, 310.8 mmol) and sodium hypophosphite hydrate (45.1g, 512.8 mmol) were refluxed for 3 hours in acetic acid solution (50OmL) . Then, the reaction product was cooled to room temperature, and solid was filtered. Next, the filtered solid was washed with water and methanol several times, and then were dried to obtain 2- bromotrianthracene of light yellow solid (15.Og, yield 79%). [Reaction Scheme 2 ]

Example 1: preparation of a compound represented by Formu] a 2 according to the present invention As described in following Reaction Scheme 3, 2- bromotrianthracene (7.Og, 11.5 mmol) prepared by Preparation Example 2, and 2-naphthaleneboron i_c acid (4.7 g, 18.4 mmol) were dissolved in toluene (150 mL) , and then tetrakis (triphenylphosphino) palladium (0.3 g, 0.2 mmol) was added under a nitrogen atmosphere. Then, sodium carbonate (3.7 g, 34.5 mmol) dissolved in distilled water (100 mL) was added, and then, the reaction solution was refluxed and agitated for 5 hours. After the reaction was completed, the resultant product was extracted by using methylene chloride and water, and palladium was removed by high temperature filtration through a thin silica gel pad. The solvent of the organic solvent layer was evaporated by vacuum distillation, and then filtration was performed to obtain a brown solid product. The filtrate was dissolved in a small amount of methylene chloride, and was recrystallized by cooling. The crystal was filtered to obtain a compound of a light yellow solid, which is represented by Formula 2 (6.7g, yield 89%).

¹H NMR (CD₂Cl₂) δ(ppm): 7.11-7.13 (m, 2H), 7.15-7.16 (m, IH), 7.18-7.22 (m, 2H), 7.34-7.38 (m, 7H), 7.41-7.45 (m, 4H), 7.53-7.58 (m, 6H), 7.62-7.68 (m, 4H), 8.26-8.29 (t, J=7.7Hz,

4H), 8.82-8.83 (d, J=5.8Hz, 2H); FD-MS: m/z 656 (M⁺); Elemental analysis: calcd. For C₅₂H₃₂: C 95.09%, H 4.91%; found: C 95.28%, H 4.71%. [Reaction Scheme 3 ]

Preparation Example 3 : preparation of a compound b

As described in following Reaction Scheme 4, 9- bromoanthracene (14.8g, 57.4 mmol) was dissolved in purified

THF (350M1) under a nitrogen atmosphere, was cooled to -78^°C, and then, n-butyllithium hexane solution (42.7mL, 1.6 M) was slowly added to the resultant mixture. After agitation for 1 hour at the same temperature, 2, β-dibromoanthraquinone (10. Og, 27.3 mmol) was added to the reaction product at the same temperature. Then, after a cooling container was removed, the reaction product was agitated for 5 hours at room temperature.

Next, after the reaction solution was removed, the resultant product was subjected to solvent extraction using water and dichloromethane, and then the used solvent was removed. The resultant product was sufficiently cleaned by n-hexane, and was vacuum-dried to obtain a compound b of light brown solid

(9.2g, yield 49%) .

[Reaction Scheme 4 ]

Preparation Example 4 : preparation of 2, 6- dibromotrianthracene

As described in following Reaction Scheme 5, the compound b (18.5g, 25.6 mmol) prepared by Preparation Example 3, and a mixture of potassium iodide (42.5g, 256.1 mmol) and sodium hypophosphite hydrate (37.2g, 422.5 mmol) were refluxed for 3 hours in acetic acid solution (50OmL) . Then, the reaction product was cooled to room temperature, and solid was filtered. Next, the filtered solid was washed with water and methanol several times, and then were dried to obtain 2,6- dibromotrianthracene of brown solid (10. Og, yield 57%). [Reaction Scheme 5]

Example 2 : preparation of a compound represented by Formula 3 according to the present invention

As described in following Reaction Scheme 6, 2,6- dibromotrianthracene (8.Og, 11.6 mmol) prepared by Preparation Example 4, and 2-naphthalene boronic acid (7.4 g, 29.0 mmol) were dissolved in toluene (200 mL) , and then tetrakis (triphenylphosphino) palladium (0.7 g, 0.6 mmol) was added under a nitrogen atmosphere. Then, sodium carbonate (15.4 g, 145.0 mmol) dissolved in distilled water (150 mL) was added, and then the reaction solution was refluxed and agitated for 5 hours. After the reaction was completed, the resultant product was extracted by using methylene chloride and water, and palladium was removed by high temperature filtration through a thin silica gel pad. The solvent of the organic solvent layer was evaporated by vacuum distillation, and then filtration was performed to obtain a brown solid product. The filtrate was dissolved in a small amount of methylene chloride, and was recrystallized by cooling. The crystal was filtered to obtain a compound of a yellow solid, which is represented by Formula 3 (8.1g, yield 87%).

¹H NMR (CD₂Cl₂) δ(ppm): 7.12-7.16 (m, 8H), 7.31-7.35 (m, 8H), 7.40-7.42 (m, 2H), 7.55-7.62 (m, 14H), 8.31-8.35 (m, 4H),

.72-8.76 (d, J=5.2Hz, 2H); FD-MS: m/z 782 (M⁺ Elemental analysis: calcd. For C₅₂H₃₈: C 95.11%, H 4.89%; found: C 95.31%, H 4.67%.

[Reaction Scheme 6]

Experimental Example 1: determination on optical characteristics

On each of compounds represented by Formulas 2 and 3 prepared by Examples 1 and 2, optical characteristics such as UV absorbance, polarized light (PL) absorbance, energy level, and band gap were determined. The results are shown in the following Table 3. [Table 3]

PL

UV (abs .) HOMO LUMO (λmax) Eg

Inv-1 316 nm, 366 nm 440 nm 5.90 eV 2 76 eV 3.14 eV

Inv-2 320 nm, 368 nm 446 nm 5.92 eV 2 83 eV 3.09 eV

Experimental Example 2: determination on device characteristics of the compound represented by Formula 2 (1) A device was manufactured in such a manner that the compound represented by Formula 2 according to Example 1 (which is used as a green host material) , and a green dopant according to Table 4 are included, and then the device characteristics were determined. The results are shown in the following Table 5. [Table 4]

[Table 5]

Experimental Example 3: determination on device characteristics of the compound represented by Formula 2 (2)

A device was manufactured in such a manner that the compound represented by Formula 2 according to Example 1 (which is used as a blue host material) , and a blue dopant according to Table 6 are included, and then the device characteristics were determined. The results are shown in the following Table 7. [Table β]

[Table 7]

Experimental Example 4 : determination on device characteristics of the compound represented by Formula 3 (1)

A device was manufactured in such a manner that the compound represented by Formula 3 according to Example 2 (which is used as a green host material) , and a green dopant according to Table 8 are included, and then the device characteristics were determined. The results are shown in the following Table 9. [Table 8]

[Table 9]

Experimental Example 5: determination on device characteristics of the compound represented by Formula 3 (2)

A device was manufactured in such a manner that the compound represented by Formula 3 according to Example 2 (which is used as a blue host material) , and a blue dopant according to Table 10 are included, and then the device characteristics were determined. The results are shown in the following Table 11. [Table 10]

[Table 11]

[industrial Applicability]

As can be seen from the foregoing, an organic electroluminescence (EL) layer or device according to the present invention, which comprises a diaryl trianthracene compound represented by Formula 1 with two aryl groups disposed at specific positions, significantly improves the lifetime of a device, the light-emitting efficiency, and the driving capability with a low voltage.

While this invention has been described in connection with what is presently considered to be the most practical and exemplary embodiment, it is to be understood that the invention is not limited to the disclosed embodiment and the drawings, but, on the contrary, it is intended to cover various modifications and variations within the spirit and scope of the appended claims.

Claims

[CLAIMS]

[Claim l]

A diaryl trianthracene derivative represented by Formula

1:

[ Formula 1 ]

in the formula, Ari and Ar₂ are the same or different from each other, and each of Ari and Ar₂ is independently an aryl group or an aromatic ring selected from the group including benzene, naphthalene, biphenyl, and anthracene; and Ri ~ R₂₄ are the same or different from each other, and each of Ri ~ R₂₄ is independently selected from the group including hydrogen, a halogen group, a substituted or unsubstituted Ci~C₃o alkyl group, a substituted or unsubstituted Ci~C₃o alkenyl group, a substituted or unsubstituted C₅-C₃₀ aryl group, a substituted or unsubstituted Cs^C_3O arylalkyl group, a substituted or unsubstituted Cs^C_3O aryloxy group, a substituted or unsubstituted C₅-C₃O heteroaryl group, a substituted or unsubstituted C₅-Ci_O cycloalkyl group, and a substituted or unsubstituted C₅-Ci₀ heterocycloalkyl group, or form a condensed ring between adjacent substituents. [Claim 2]

The diaryl trianthracene derivative as claimed in claim 1, wherein the diaryl trianthracene derivative represented by Formula 1 is selected from the group including compounds represented by Formulas 2-5:

[Formula 2]

[Formula 3]

[Formula 4]

[Formula 5]

[Claim 3]

An organic electroluminescence layer comprising the diaryl trianthracene derivative as claimed in claim 1 or 2. [Claim 4]

An organic electroluminescence device comprising the diaryl trianthracene derivative as claimed in claim 1 or 2.