EP2694619A1

EP2694619A1 - Novel organic electroluminescent compounds and an organic electroluminescent device using the same

Info

Publication number: EP2694619A1
Application number: EP12779767.8A
Authority: EP
Inventors: Chi-Sik Kim; Soo-Jin Yang; Hee-Sook Kim; Kyoung-Jin Park; Seung-Ae Kim; Kyung-Joo Lee; Hyuck-Joo Kwon; Bong-Ok Kim
Original assignee: Rohm and Haas Electronic Materials Korea Ltd
Current assignee: Rohm and Haas Electronic Materials Korea Ltd
Priority date: 2011-05-03
Filing date: 2012-05-03
Publication date: 2014-02-12
Also published as: EP2694619A4; TW201302973A; WO2012150826A1

Abstract

An organic electroluminescent compound of formula 1 and an organic electroluminescent device comprising the same is disclosed. The organic luminescent compound provides an organic electroluminescent device which has high luminous efficiency and a long operation lifetime and requires a low driving voltage, to thereby have improved power efficiency and power consumption.

Description

NOVEL ORGANIC ELECTROLUMINESCENT COMPOUNDS AND AN ORGANIC ELECTROLUMINESCENT DEVICE USING THE SAME

The present invention relates to novel organic electroluminescent compounds and an organic electroluminescent device using the same.

An electroluminescent (EL) device is a self-light-emitting device which has advantages over other types of display devices in that it provides a wider viewing angle, a greater contrast ratio, and has a faster response time. An organic EL device was first developed by Eastman Kodak, by using small molecules which are aromatic diamines, and aluminum complexes as a material for forming a light-emitting layer [Appl. Phys. Lett. 51, 913, 1987].

The most important factor to determine luminous efficiency in an organic EL device is a light-emitting material. Until now, fluorescent materials have been widely used as a light-emitting material. However, in view of electroluminescent mechanisms, phosphorescent materials theoretically show four (4) times higher luminous efficiency than fluorescent materials. Thus, recently, phosphorescent materials have been investigated. Iridium (III) complexes have been widely known as phosphorescent materials, including bis(2-(2’-benzothienyl)-pyridinato-N,C3’)iridium (acetylacetonate) ((acac)Ir(btp)₂), tris(2-phenylpyridine)iridium (Ir(ppy)₃) and bis(4,6-difluorophenylpyridinato-N,C2)picolinate iridium (Firpic) as red, green and blue materials, respectively. In order to improve color purity, luminous efficiency and stability, light-emitting materials can be used as a system prepared by mixing a dopant with a host material. In the host material/dopant system, the host material has a great influence on the efficiency and performance of an EL device, and thus its selection is important. At present, 4,4’-bis(carbazol-9-yl)-biphenyl (CBP) is the most widely known host material for phosphorescent materials. Further, Pioneer (Japan) developed a high performance organic EL device employing, as a host material, bathocuproine (BCP) or aluminum(III)bis(2-methyl-8-quinolinate)(4-phenylphenolate) (BAlq), which had been a material used for a hole blocking layer.

Though these phosphorous host materials provide good light-emitting characteristics, they have the following disadvantages: (1) Due to their low glass transition temperature and poor thermal stability, their degradation may occur during a high-temperature deposition process in a vacuum. (2) The power efficiency of an organic EL device is given by [(π/voltage) × current efficiency], and thus the power efficiency is inversely proportional to the voltage. Though an organic EL device comprising phosphorescent materials provides higher current efficiency (cd/A) than one comprising fluorescent materials, a significantly high driving voltage is required to be applied to an organic EL device, thereby resulting in poor power efficiency (lm/W). (3) Further, the operation lifetime of an organic EL device is short and luminous efficiency is still required to be improved.

Korean Patent No. 948700 discloses compounds for organic electroluminescent materials whose arylcarbazole backbone has a nitrogen-containing aryl. However, it does not disclose compounds whose carbazole backbone has both dibenzothiophene and a nitrogen-containing aryl. Further, an organic EL device comprising said compounds fails to provide satisfactory luminous efficiency, driving voltage and operation lifetime.

An objective of the present invention is to provide organic electroluminescent compounds, which impart excellent luminous efficiency, a long operation lifetime and a low driving voltage to a device; and an organic electroluminescent device, which has high efficiency and a long operation lifetime, using said compounds.

The present inventors found that the above objective can be achieved by a compound represented by the following formula 1:

[Formula 1]

wherein

L₁and L₂each independently represent a single bond, a substituted or unsubstituted 3- to 30-membered heteroarylene group, or a substituted or unsubstituted (C6-C30)arylene group;

X₁ and X₂each independently represent CR’ or N;

Y represents S, O or -CR₂₁R₂₂;

Ar₁, Ar₂, R’, R₂₁ and R₂₂ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl group, a substituted or unsubstituted (C6-C30)aryl group, or a substituted or unsubstituted 3- to 30-membered heteroaryl group;

R₁ to R₄ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl group, a substituted or unsubstituted (C6-C30)aryl group, a substituted or unsubstituted 3- to 30-membered heteroaryl group, -NR₁₁R₁₂, -SiR₁₃R₁₄R₁₅, -SR₁₆, -OR₁₇, a cyano group, a nitro group or a hydroxyl group;

R₁₁ to R₁₇ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl group, a substituted or unsubstituted (C6-C30)aryl group or a substituted or unsubstituted 3- to 30-membered heteroaryl group; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, alicyclic or aromatic ring whose carbon atom(s) may be replaced by at least one atom selected from nitrogen, oxygen and sulfur;

a and d each independently represent an integer of 1 to 4; where a or d is an integer of 2 or more, each of R₁ or each of R₄ is the same or different;

b and c each independently represent an integer of 1 to 3; where b or c is an integer of 2 or more, each of R₂ or each of R₃ is the same or different; and the heteroaryl group and the heteroarylene group contain at least one atom selected from B, N, O, S, P(=O), Si and P.

Substituents of the substituted groups in L₁, L₂, Ar₁, Ar₂, R’, R₁ to R₄, R₁₁ to R₁₇, R₂₁ and R₂₂ each independently are at least one selected from the group consisting of deuterium, a halogen, a (C1-C30)alkyl group, a (C1-C30)alkyl group substituted with a halogen, a (C6-C30)aryl group, a 3- to 30-membered heteroaryl group, a 3- to 30-membered heteroaryl group substituted with a (C6-C30)aryl group, a (C6-C30)aryl group substituted with a 3- to 30-membered heteroaryl group, a (C3-C30)cycloalkyl group, a 5- to 7-membered heterocycloalkyl group, a tri(C1-C30)alkylsilyl group, a tri(C6-C30)arylsilyl group, a di(C1-C30)alkyl(C6-C30)arylsilyl group, a (C1-C30)alkyldi(C6-C30)arylsilyl group, a (C2-C30)alkenyl group, a (C2-C30)alkynyl group, a cyano group, a di(C1-C30)alkylamino group, a di(C6-C30)arylamino group, a (C1-C30)alkyl(C6-C30)arylamino group, a di(C6-C30)arylboronyl group, a di(C1-C30)alkylboronyl group, a (C1-C30)alkyl(C6-C30)arylboronyl group, a (C6-C30)aryl(C1-C30)alkyl group, a (C1-C30)alkyl(C6-C30)aryl group, a carboxyl group, a nitro group and a hydroxyl group.

Herein, the terms “alkyl,” “alkoxy” and any “alkyl” moiety which is comprised in substituents include both a linear structure and a branched structure; and the term “cycloalkyl” includes a mono- or polycyclic hydrocarbon such as a substituted or unsubstituted adamantyl group or a substituted or unsubstituted (C7-C30)bicycloalkyl group. The term “aryl” refers to an organic radical derived from an aromatic hydrocarbon by removing one hydrogen atom; includes a monocyclic ring or fused ring each of whose rings has 4 to 7, preferably 5 or 6, ring backbone atoms; may be one formed by linking two or more aryl groups to one another via a single bond(s); and includes phenyl, biphenyl, terphenyl, naphthyl, anthryl, indenyl, fluorenyl, phenanthrenyl, triphenylenyl, pyrenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, etc., wherein said naphthyl includes 1-naphthyl and 2-naphthyl, said anthryl includes 1-anthryl, 2-anthryl and 9-anthryl and said fluorenyl includes 1-fluorenyl, 2-fluorenyl, 3-fluorenyl, 4-fluorenyl and 9-fluorenyl. The term “heteroaryl” refers to an aryl having 1 to 4 heteroatoms selected from the group consisting of B, N, O, S, P(=O), Si and P, and carbon atoms as remaining ring backbone atoms other than said heteroatom; is a monocyclic ring or fused ring condensed with at least one benzene ring; may be partially saturated; may be one formed by linking at least one heteroaryl group to other heteroaryl or aryl group via a single bond(s); may be a divalent aryl group whose ring backbone heteroatom is oxidized or quaternarized, for example, to form a N-oxide or a quaternary salt; and includes a monocyclic ring-type heteroaryl including furyl, thiophenyl, pyrrolyl, imidazolyl, pyrazolyl, thiazolyl, thiadiazolyl, isothiazolyl, isoxazolyl, oxazolyl, oxadiazolyl, triazinyl, tetrazinyl, triazolyl, tetrazolyl, furazanyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, etc., a fused ring-type heteroaryl including benzofuranyl, benzothiophenyl, isobenzofuranyl, benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzoisoxazolyl, benzoxazolyl, isoindolyl, indolyl, indazolyl, benzothiadiazolyl, quinolyl, isoquinolyl, cinnolinyl, quinazolinyl, quinoxalinyl, carbazolyl, phenanthridinyl, benzodioxolyl, dibenzofuranyl, dibenzothiophenyl, etc., N-oxides thereof (for example, pyridyl N-oxide, quinolyl N-oxide) and quaternary salts thereof.

Further, the “(C1-C30)alkyl(ene)” group is preferably a (C1-C20)alkyl(ene) group and more preferably a (C1-C10)alkyl(ene) group; the “(C6-C30)aryl(ene)” group is preferably a (C6-C20)aryl(ene) group and more preferably a (C6-C12)aryl(ene) group; the “3- to 30-membered heteroaryl(ene)” group is preferably a 3- to 20-membered heteroaryl(ene) group and more preferably a 5- to 13-membered heteroaryl(ene) group; the “(C3-C30)cycloalkyl” group is preferably a (C3-C20)cycloalkyl group and more preferably a (C3-C7)cycloalkyl group; and the “(C2-C30)alkenyl(ene) or alkynyl(ene)” group is preferably a (C2-C20)alkenyl(ene) or alkynyl(ene) group and more preferably a (C2-C10)alkenyl(ene) or alkynyl(ene) group.

Preferably, L₁ and L₂ each independently represent a single bond; or a substituted or unsubstituted phenylene, biphenylene, terphenylene, indenylene, fluorenylene, triphenylenylene, pyrenylene, perylenylene, chrysenylene, naphthacenylene, fluoranthenylene, thiophenylene, pyrrolylene, pyrazolylene, thiazolylene, oxazolylene, oxadiazolylene, triazinylene, tetrazinylene, triazolylene, tetrazolylene, furazanylene, pyridylene, benzofuranylene, benzothiophenylene, indolene, benzoimidazolylene, benzothiazolylene, benzoisothiazolylene, benzoisoxazolylene, benzoxazolylene, benzothiadiazolylene, dibenzofuranylene or dibenzothiophenylene;

Ar₁, Ar₂, R’, R₂₁ and R₂₂ each independently represent hydrogen; or a substituted or unsubstituted methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, decyl, dodecyl, hexadecyl, trifluoromethyl, perfluoroethyl, trifluoroethyl, perfluoropropyl, perfluorobutyl, phenyl, biphenyl, fluorenyl, fluoranthenyl, terphenyl, pyrenyl, chrysenyl, naphthacenyl, perylene, pyridyl, pyrrolyl, furanyl, thiophenyl, imidazolyl, benzoimidazolyl, quinolyl, triazinyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, pyrazolyl, indolyl, carbazolyl, thiazolyl, oxazolyl, benzothiazolyl, benzoxazolyl, phenanthrolinyl, quinoxalinyl or N-carbazolyl; more preferably, R₂₁ and R₂₂ each independently represent hydrogen, methyl, ethyl, n-propyl or i-propyl;

R₁ to R₄ each independently represent hydrogen, deuterium, chloro, fluoro, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, decyl, dodecyl, hexadecyl, trifluoromethyl, perfluoroethyl, trifluoroethyl, perfluoropropyl, perfluorobutyl, phenyl, biphenyl, fluorenyl, fluoranthenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, perylenyl, pyridyl, pyrrolyl, furanyl, thiophenyl, imidazolyl, benzoimidazolyl, indenyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinolyl, triazinyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, pyrazolyl, indolyl, carbazolyl, thiazolyl, oxazolyl, benzothiazolyl, benzoxazolyl, phenanthrolinyl or N-carbazolyl;

a to d each independently represent an integer of 1 to 2, more preferably 1; and

L₁, L₂, Ar₁, Ar₂, R’, R₁ to R₄, R₂₁ and R₂₂ each independently may be further substituted with at least one selected from the group consisting of deuterium, chloro, fluoro, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, decyl, dodecyl, hexadecyl, trifluoromethyl, perfluoroethyl, trifluoroethyl, perfluoropropyl, perfluorobutyl, phenyl, biphenyl, fluorenyl, fluoranthenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, perylenyl, fluorotrimethylsilyl, triethylsilyl, tripropylsilyl, tri(t-butyl)silyl, t-butyldimethylsilyl, dimethylphenylsilyl, carbazolyl and triphenylsilyl, and more preferably at least one selected from the group consisting of deuterium, chloro, fluoro, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ehtylhexyl, n-nonyl and decyl.

Organic electroluminescent compounds according to the present invention include the following, but are not limited thereto:

Organic electroluminescent compounds according to the present invention can be prepared according to the following reaction scheme 1.

[Reaction Scheme 1]

wherein Ar₁, Ar₂, L₁, L₂, Y, X₁, X₂, R₁ to R₄, a, b, c and d are as defined in formula 1 above, and X represents a halogen.

In addition, the present invention provides an organic electroluminescent device comprising the compound of formula 1. The organic electroluminescent device comprises a first electrode, a second electrode and at least one organic layer between the first and second electrodes. The organic layer comprises at least one compound of formula 1 according to the present invention. One of the first electrode and the second electrode is an anode and the other is a cathode. The organic layer comprises a light-emitting layerand may further comprise at least one layer selected from a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, an interlayer and a hole blocking layer.

The compound of formula 1 is comprised in at least one of the light-emitting layer and the hole transport layer. Where the hole transport layer comprises the compound of formula 1, the compound may be used as a hole transport material. Where the light-emitting layer comprises the compound of formula 1, the compound may be used as a host material; preferably, the light-emitting layer may further comprise at least one dopant; and if necessary, the light-emitting layer may further comprise another host material in addition to the compound of formula 1.

As the dopant, at least one phosphorescent dopant is preferable. In the organic electroluminescent device of the present invention, the phosphorescent dopant is not particularly limited; however, preferably, a complex compound comprising a metal atom selected from iridium (Ir), osmium (Os), copper (Cu) and platinum (Pt), more preferably an ortho-metalated complex compound comprising a metal atom selected from Ir, Os, Cu and Pt, and even more preferably, an ortho-metalated complex compound comprising Ir is comprised.

Further, it is preferable to select the phosphorescent dopant from the group consisting of compounds represented by the following formulae 2 to 4:

[Formula 2]

[Formula 3]

[Formula 4]

wherein

L is selected from the following structure:

R₁₀₀ represents hydrogen or a substituted or unsubstituted (C1-C30)alkyl group; R₁₀₁ to R₁₀₉and R₁₁₁ to R₁₂₇ each independently represent hydrogen, deuterium, a halogen, a (C1-C30)alkyl group substituted or unsubstituted with a halogen, a cyano group, or a substituted or unsubstituted (C1-C30)alkoxy group; R₂₀₁ to R₂₁₁ each independently represent hydrogen, deuterium, a halogen, or a (C1-C30)alkyl group substituted or unsubstituted with a halogen; f and g each independently represent an integer of 1 to 3; h represents an integer of 1 to 2; where f, g, or h are integers of 2 or more, each of R₁₀₀ is the same or different; and n represents an integer of 1 to 3.

The phosphorescent dopant includes the following

The organic electroluminescent device of the present invention comprises a first electrode, a second electrode and at least one organic layer between the first electrode and the second electrode; the organic layer comprises a light-emitting layer; the light-emitting layer comprises a composition for the organic electroluminescent device of the present invention and a phosphorous dopant; and the composition for the organic electroluminescent device is used as a host material.

The organic electroluminescent device of the present invention may further comprise, in addition to the compound of formula 1, at least one compound selected from the group consisting of arylamine-based compounds and styrylarylamine-based compounds in the organic layer.

In the organic electroluminescent device of the present invention, the organic layer may further comprise, in addition to the compound of formula 1, at least one metal selected from the group consisting of metals of Group 1, metals of Group 2, transition metals of the 4^th period, transition metals of the 5^th period, lanthanides and organic metals of d-transition elements of the Periodic Table, or at least one complex compound comprising said metal. Further, the organic layer may comprise a light-emitting layer and a charge generating layer.

The organic electroluminescent device of the present invention may emit a white light by further comprising at least one light-emitting layer which comprises a blue electroluminescent compound, a red electroluminescent compound or a green electroluminescent compound, in addition to the compound of the present invention. If necessary, the organic electroluminescent device may further comprise a yellow light-emitting layer or an orange light-emitting layer.

Preferably, in the organic electroluminescent device of the present invention, at least one layer (hereinafter, “a surface layer”) selected from a chalcogenide layer, a metal halide layer and a metal oxide layer may be placed on an inner surface(s) of one or both electrode(s). Specifically, it is preferred that the chalcogenide (includes oxides) layer of silicon or aluminum is placed on an anode surface of an electroluminescent medium layer, and the metal halide layer or metal oxide layer is placed on a cathode surface of an electroluminescent medium layer. Such a surface layer provides operation stability for the organic electroluminescent device. Preferably, said chalcogenide includes SiO_X(1≤X≤2), AlO_X(1≤X≤1.5), SiON, SiAlON, etc.; said metal halide includes LiF, MgF₂, CaF₂, a rare earth metal fluoride, etc.; and said metal oxide includes Cs₂O, Li₂O, MgO, SrO, BaO, CaO, etc.

Preferably, in the organic electroluminescent device of the present invention, a mixed region of an electron transport compound and a reductive dopant, or a mixed region of a hole transport compound and an oxidative dopant may be placed on at least one surface of a pair of electrodes. In that case, the electron transport compound is reduced to an anion, and thus it becomes easier to inject and transport electrons from the mixed region to the electroluminescent medium. Further, the hole transport compound is oxidized to a cation, and thus it becomes easier to inject and transport holes from the mixed region to the electroluminescent medium. Preferably, the oxidative dopant includes various Lewis acids and acceptor compounds; and the reductive dopant includes alkali metals, alkali metal compounds, alkaline earth metals, rare-earth metals, and mixtures thereof. A reductive dopant layer may be employed as a charge generating layer to prepare an electroluminescent device having two or more electroluminescent layers and emitting a white light.

The organic electroluminescent compound of the present invention provides an organic electroluminescent device which has high luminous efficiency and a long operation lifetime and requires a low driving voltage, to thereby have improved power efficiency and power consumption.

Hereinafter, the preparation method of the organic electroluminescent compound, and the luminescent properties of the organic electroluminescent devices using the compound of the present invention will be explained in detail with reference to the following examples.

The abbreviations used in the examples have the following meanings:

EA: ethyl acetate, THF: tetrahydrofuran, MC: methylene chloride, n-Bu: normal-butyl,

DMF: dimethylformamide, DME: dimethylether, i-Pr: isopropyl, and EtOH: ethanol

[Preparation Example 1] Preparation of compound C-31

Preparation of compound A-2

Compound A-1 20 g (0.087 mol), 4-bromoiodobenzene 49.6 g (0.175 mol), Pd(PPh₃)₄ 3.039g (0.0026 mol), 1 M Na₂CO₃ and toluene 400 mL were mixed and stirred under reflux. After 3 hours, the mixture was cooled to room temperature, and then distilled water was added thereto. The mixture was extracted with EA and was dried with MgSO₄. The obtained solid was distilled under reduced pressure and was purified by column chromatography to obtain compound A-2 (23 g, 0.065 mol, 75.6%).

Preparation of compound A-3

Compound A-2 23 g (0.065 mol) was dissolved in THF 700 mL. n-BuLi 39 mL (0.098 mol, 2.5 M in hexane) was slowly added at -78°C to the mixture. After 1 hour, triisopropylborate 30.2 mL (0.131 mol) was added thereto. After stirring the mixture at room temperature for 12 hours and adding distilled water thereto, the mixture was extracted with EA, was dried with MgSO₄, and was distilled under reduced pressure. The resultant was recrystallized with MC and hexane to obtain compound A-3 (15 g, 0.049 mol, 75.38%).

Preparation of compound A-4

Compound A-3 15 g (49.31 mmol), 2-bromonitrobenzene 12.9 g (64.10 mmol), Pd(PPh₃)₄ 1.13 g (0.98 mmol), 2 M Na₂CO₃ 60 mL, toluene 150 mL and ethanol 50 mL were mixed and were stirred under reflux. After 4 hours, the mixture was cooled to room temperature. After adding distilled water to the mixture, it was extracted with EA and was dried with MgSO₄. The resultant was distilled under reduced pressure and was recrystallized with MC and hexane to obtain compound A-4 (13.5 g, 35.39 mmol, 71.77%).

Preparation of compound A-5

Compound A-4 13.5 g, triethylphosphite 150 mL and 1,2-dichlorobenzene 150 mL were mixed and were stirred at 150°C for 10 hours. The mixture was cooled to room temperature, was distilled under reduced pressure, and was purified by column chromatography to obtain compound A-5 (8 g, 22.89 mmol, 65.4%).

Preparation of compound A-7

Compound A-6 20 g (72.96 mmol), 2,4-dichloropyrimidine 9.8 g (66.32 mmol), Pd(PPh₃)₄ 2.28 g (1.97 mmol), 2 M Na₂CO₃ 80 mL and DME 200 mL were mixed and were stirred under reflux for 12 hours. The mixture was cooled to room temperature and distilled water was added thereto. The resultant was extracted with EA, was dried with MgSO₄ and was distilled under reduced pressure. Compound A-7 (9 g, 26.25 mmol, 39.77%) was obtained via column chromatography.

Preparation of compound C-31

Compound A-7 5 g (14.58 mmol) and compound A-5 6.11 g (17.50 mmol) were dissolved in DMF 120 mL, and then NaH 0.52 g (21.87 mmol) was added thereto. The mixture was stirred at room temperature for 12 hours and methanol was added thereto. The obtained solid was filtered under reduced pressure and was recrystallized with EA and CHCl₃ to obtain compound C-31 (6.5 g, 9.91 mmol, 67.97%).

MS/FAB Found 656; Calculated 655.21

[Preparation Example 2] Preparation of compound C-41

Preparation of compound 2-2

Compound 2-1 25 g (0.126 mol), 4-bromoiodobenzene 89.3 g (0.316 mol), PdCl₂(PPh₃)₂ 2.66 g (0.0038 mol), 2M Na₂CO₃ 150 mL, toluene 150 mL and ethanol 30 mL were mixed, were stirred at 110°C for 3 hours, and then distilled water was added thereto. The mixture was extracted with EA, was dried with MgSO₄, and was distilled under reduced pressure. Compound 2-2 31 g (0.100 mol, 80%) was obtained by purifying via column chromatography.

Preparation of compound 2-3

Compound 2-2 31 g (0.100 mol) was dissolved in THF 750 mL, and then n-BuLi 60 mL (0.150 mol, 2.5 M in hexane) was slowly added at -78°C. After 1 hour, triisopropylborate 46 mL (0.200 mol) was added to the mixture. The mixture was stirred at room temperature for 12 hours, and distilled water was added thereto. Then, the mixture was extracted with EA, was dried with MgSO₄, and was distilled under reduced pressure. After recrystallizing with MC and hexane, compound 2-3 21 g (0.076 mol, 76.6%) was obtained.

Preparation of compound 2-4

2,4-dichloropyrimidine 7 g (0.047 mol), compound 2-3 10 g (0.036 mol), 2M Na₂CO₃ 45 mL, toluene 182 mL and ethanol 45 mL were mixed. The mixture was stirred under reflux for 12 hours, and then was cooled to room temperature. After adding distilled water thereto, the mixture was extracted with EA, was dried with MgSO₄, and was distilled under reduced pressure. Compound 2-4 9 g (0.026 mol, 72.9%) was obtained by purifying via column chromatography.

Preparation of compound C-41

Compound 2-4 5 g (14.58 mmol) and compound A-5 6.11 g (17.50 mmol) were dissolved in DMF 120 mL, and then NaH 0.52 g (21.87 mmol) was added thereto. The mixture was stirred at room temperature for 12 hours, and then methanol was added thereto. The obtained solid was filtered under reduced pressure and was recrystallized with EA and CHCl₃ to obtain compound C-41 6.0 g (0.009 mol, 62.75%).

MS/FAB Found 658; Calculated 657.22

[Preparation Example 3] Preparation of compound C-53

Preparation of compound C-53

Compound 3-1, 4-([1,1’-biphenyl]-4-yl)-2-chloro-6-phenylpyrimidine (5 g, 14.58 mmol) and compound A-5 (5.6 g, 16.04 mmol) were dissolved in DMF 100 mL, and then NaH (0.87 g, 60% in mineral oil, 21.87 mmol) was added thereto. The mixture was stirred at room temperature for 12 hours. After adding methanol, the mixture was filtered under reduced pressure. Compound C-53 (7 g, 10.67 mmol, 73.2%) was obtained by purifying the obtained solid via column chromatography.

MS/FAB Found 655.8; Calculated 655.21

[Preparation Example 4] Preparation of compound C-64

Preparation of compound C-64

2-chloro-4,6-diphenyl-1,3,5-triazine (3.1 g, 11.4 mmol) and compound A-5 (4 g, 11.4 mmol) was suspended in DMF 57 mL, and then 60% NaH (684 mg, 17.1 mmol) was added thereto at room temperature. The mixture was stirred for 12 hours. After adding distilled water (1L), the mixture was filtered under reduced pressure. The obtained solid was purified via column chromatography to obtain compound C-64 (2.4 g, 36.4%).

MS/FAB Found 580.7; Calculated 580.17

[Preparation Example 5] Preparation of compound C-66

Preparation of compound 5-1

Compound A-5 (10 g, 0.03 mol), 1-bromo-4-iodobenzene (16 g, 0.06 mol), CuI (2.7 g, 0.01 mol), ethylenediamine (1.9 mL, 0.03 mol), K₃PO₄ (15 g, 0.07 mol) and toluene (150 mL) were mixed. The mixture was stirred at 120°C for 12 hours, and then was extracted with EA. The obtained organic layer was dried with MgSO₄ and then was filtered. After removing solvents under reduced pressure, the obtained solid was purified via column chromatography to obtain compound 5-1 (13 g, 91%).

Preparation of compound 5-2

Dry THF (200 mL) and compound 5-1 (13 g, 0.03 mol) were mixed. While stirring under nitrogen atmosphere, n-BuLi (16 mL, 2.25 M solution in hexane) was slowly added to the mixture at -78°C. The mixture was stirred at -78°C for 1 hour and B(O-iPr)₃ (12 mL, 0.05 mol) was slowly added thereto at -78°C. Then, the mixture was warmed to room temperature and was reacted together for 12 hours. After completing the reaction, the resultant was extracted with EA. The obtained organic layer was dried with MgSO₄ and was filtered. After removing solvents under reduced pressure, the obtained solid was recrystallized to obtain compound 5-2 (11g, 90%).

Preparation of compound C-66

Compound 5-2 (11 g, 0.02 mol), 2-chloro-4,6-diphenyl-1,3,5-triazine (8.2 g, 0.03 mol), Pd(PPh₃)₄ (1.35 g, 0.001 mol), K₂CO₃ (9.7 g, 0.07 mol), toluene (120 mL), EtOH (30 mL) and H₂O (35 mL) were mixed. The mixture was stirred at 120°C for 12 hours. After completing the reaction, the resultant was extracted with EA. The obtained organic layer was dried with MgSO₄ and was filtered. After removing solvents under reduced pressure, the obtained solid was recrystallized to obtain compound C-66 (8.3 g, 54%).

MS/FAB Found 656.8; Calculated 656.2

[Example 1] Production of an OLED device using the compound of the present invention

A transparent electrode indium tin oxide (ITO) thin film (15 Ω/sq) on a glass substrate for an OLED device (Samsung Corning, Republic of Korea) was subjected to an ultrasonic washing with trichloroethylene, acetone, ethanol and distilled water, sequentially, and then was stored in isopropanol. Then, the ITO substrate was mounted on a substrate holder of a vacuum vapor depositing apparatus. 2-TNATA [4,4’,4”-tris(N,N-(2-naphthyl)phenylamino)triphenylamine] was introduced into a cell of said vacuum vapor depositing apparatus, and then the pressure in the chamber of said apparatus was controlled to 10^-6 torr. Thereafter, an electric current was applied to the cell to evaporate 2-TNATA, thereby forming a hole injection layer having a thickness of 60 nm on the ITO substrate. Then, NPB [N,N’-bis(α-naphthyl)-N,N’-diphenyl-4,4’-diamine] was introduced into another cell of said vacuum vapor depositing apparatus, and was evaporated by applying electric current to the cell, thereby forming a hole transport layer having a thickness of 20 nm on the hole injection layer. Thereafter, compound C-31 was introduced into one cell of the vacuum vapor depositing apparatus, as a host material, and compound D-1 was introduced into another cell as a dopant. The two materials were evaporated at different rates and was deposited in a doping amount of 4 to 20 wt% to form a light-emitting layer having a thickness of 30 nm on the hole transport layer. Then, 9,10-di(1-naphthyl)-2-(4-phenyl-1-phenyl-1H-benzo[d]imidazole)anthracene was introduced into one cell and lithium quinolate was introduced into another cell. The two materials were evaporated at different rates and were deposited in a doping amount of 30 to 70 wt% to form an electron transport layer having a thickness of 30 nm on the light-emitting layer. Then, after depositing lithium quinolate as an electron injection layer having a thickness of 1 to 2 nm on the electron transport layer, an Al cathode having a thickness of 150 nm was deposited by another vacuum vapor deposition apparatus on the electron injection layer. Thus, an OLED device was produced. All the materials used for producing the OLED device were those purified by vacuum sublimation at 10^-6 torr.

The produced OLED device showed green-light emission having a luminance of 1,000 cd/m²and a current density of 2.41 mA/cm² at a driving voltage of 3.2 V.

[Example 2] Production of an OLED device using the compound of the present invention

An OLED device was produced in the same manner as one of Example 1, except for using compound C-31 and compound D-28 as a host material and a dopant, respectively. The produced OLED device showed orange-light emission having a luminance of 1,000 cd/m² and a current density of 2.55 mA/cm² at a driving voltage of 3.7 V.

[Example 3] Production of an OLED device using the compound of the present invention

An OLED device was produced in the same manner as one of Example 1, except for using compound C-31 and compound D-44 as a host material and a dopant, respectively. The produced OLED device showed dark orange-light emission having a luminance of 1,000 cd/m² and a current density of 6.67 mA/cm² at a driving voltage of 4.0 V.

[Example 4] Production of an OLED device using the compound of the present invention

An OLED device was produced in the same manner as one of Example 1, except for using compound C-41 and compound D-1 as a host material and a dopant, respectively. The produced OLED device showed green-light emission having a luminance of 1,000 cd/m² and a current density of 2.46 mA/cm² at a driving voltage of 3.1 V.

[Example 5] Production of an OLED device using the compound of the present invention

An OLED device was produced in the same manner as one of Example 1, except for using compound C-66 and compound D-1 as a host material and a dopant, respectively. The produced OLED device showed green-light emission having a luminance of 1,000 cd/m² and a current density of 2.65 mA/cm² at a driving voltage of 3.0 V.

[Example 6] Production of an OLED device using the compound of the present invention

An OLED device was produced in the same manner as one of Example 1, except for using compound C-53 and compound D-1 as a host material and a dopant, respectively. The produced OLED device showed green-light emission having a luminance of 1,000 cd/m² and a current density of 2.56 mA/cm² at a driving voltage of 3.0 V.

[Comparative Example 1] Production of an OLED device using a conventional electroluminescent compound

An OLED device was produced in the same manner as one of Example 1, except for depositing a light-emitting layer having a thickness of 30 nm on the hole transport layer by using CBP as a host material and compound D-1 as a dopant and depositing a hole blocking layer having a thickness of 10 nm by using BAlq.

The produced OLED device showed green-light emission having a luminance of 1,000 cd/m² and a current density of 2.86 mA/cm² at a driving voltage of 4.9 V.

[Comparative Example 2] Production of an OLED device using a conventional electroluminescent compound

An OLED device was produced in the same manner as one of Example 1, except for depositing a light-emitting layer having a thickness of 30 nm on the hole transport layer by using CBP as a host material and compound D-28 as a dopant and depositing a hole blocking layer having a thickness of 10 nm by using BAlq.

The produced OLED device showed orange-light emission having a luminance of 1,000 cd/m² and a current density of 3.05 mA/cm² at a driving voltage of 4.6 V.

[Comparative Example 3] Production of an OLED device using a conventional electroluminescent compound

An OLED device was produced in the same manner as one of Comparative Example 1, except for using compound D-44 as a dopant.

The produced OLED device showed dark orange-light emission having a luminance of 1,000 cd/m² and a current density of 8.2 mA/cm² at a driving voltage of 5.2 V.

As shown above, the compounds of the present invention have superior luminescent properties than conventional compounds, and thus provide an organic electroluminescent device which has high luminous efficiency and requires a low driving voltage, to thereby have improved power efficiency and power consumption.

Claims

An organic electroluminescent compound represented by the following formula 1:

[Formula 1]

wherein

L₁ and L₂each independently represent a single bond, a substituted or unsubstituted 3- to 30-membered heteroarylene group, or a substituted or unsubstituted (C6-C30)arylene group;

X₁ and X₂ each independently represent CR’ or N;

Y represents S, O or -CR₂₁R₂₂;

Ar₁, Ar₂, R’, R₂₁ and R₂₂ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl group, a substituted or unsubstituted (C6-C30)aryl group, or a substituted or unsubstituted 3- to 30-membered heteroaryl group;

R₁ to R₄ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl group, a substituted or unsubstituted (C6-C30)aryl group, a substituted or unsubstituted 3- to 30-membered heteroaryl group, -NR₁₁R₁₂, -SiR₁₃R₁₄R₁₅, -SR₁₆, -OR₁₇, a cyano group, a nitro group or a hydroxyl group;

R₁₁ to R₁₇ each independently represent hydrogen, deuterium, a halogen, a substituted or unsubstituted (C1-C30)alkyl group, a substituted or unsubstituted (C6-C30)aryl group or a substituted or unsubstituted 3- to 30-membered heteroaryl group; or are linked to an adjacent substituent(s) to form a mono- or polycyclic, alicyclic or aromatic ring whose carbon atom(s) may be replaced by at least one atom selected from nitrogen, oxygen and sulfur;

a and d each independently represent an integer of 1 to 4; where a or d is an integer of 2 or more, each of R₁ or each of R₄ is the same or different;

b and c each independently represent an integer of 1 to 3; where b or c is an integer of 2 or more, each of R₂ or each of R₃ is the same or different; and

the heteroaryl group and the heteroarylene group contain at least one heteroatom selected from B, N, O, S, P(=O), Si and P.
The organic electroluminescent compound according to claim 1, wherein the substituents of the substituted groups in L₁, L₂, Ar₁, Ar₂, R’, R₁ to R₄, R₁₁ to R₁₇, R₂₁ and R₂₂ each independently are at least one selected from the group consisting of deuterium, a halogen, a (C1-C30)alkyl group, a (C1-C30)alkyl group substituted with a halogen, a (C6-C30)aryl group, a 3- to 30-membered heteroaryl group, a 3- to 30-membered heteroaryl group substituted with a (C6-C30)aryl group, a (C6-C30)aryl group substituted with a 3- to 30-membered heteroaryl group, a (C3-C30)cycloalkyl group, a 5- to 7-membered heterocycloalkyl group, a tri(C1-C30)alkylsilyl group, a tri(C6-C30)arylsilyl group, a di(C1-C30)alkyl(C6-C30)arylsilyl group, a (C1-C30)alkyldi(C6-C30)arylsilyl group, a (C2-C30)alkenyl group, a (C2-C30)alkynyl group, a cyano group, a di(C1-C30)alkylamino group, a di(C6-C30)arylamino group, a (C1-C30)alkyl(C6-C30)arylamino group, a di(C6-C30)arylboronyl group, a di(C1-C30)alkylboronyl group, a (C1-C30)alkyl(C6-C30)arylboronyl group, a (C6-C30)aryl(C1-C30)alkyl group, a (C1-C30)alkyl(C6-C30)aryl group, a carboxyl group, a nitro group and a hydroxyl group.
The organic electroluminescent compound according to claim 1, wherein L₁ and L₂ each independently represent a single bond; or a substituted or unsubstituted phenylene, biphenylene, terphenylene, indenylene, fluorenylene, triphenylenylene, pyrenylene, perylenylene, chrysenylene, naphthacenylene, fluoranthenylene, thiophenylene, pyrrolylene, pyrazolylene, thiazolylene, oxazolylene, oxadiazolylene, triazinylene, tetrazinylene, triazolylene, tetrazolylene, furazanylene, pyridylene, benzofuranylene, benzothiophenylene, indolene, benzoimidazolylene, benzothiazolylene, benzoisothiazolylene, benzoisoxazolylene, benzoxazolylene, benzothiadiazolylene, dibenzofuranylene or dibenzothiophenylene;

Ar₁, Ar₂, R’, R₂₁ and R₂₂ each independently represent hydrogen; or a substituted or unsubstituted methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, decyl, dodecyl, hexadecyl, trifluoromethyl, perfluoroethyl, trifluoroethyl, perfluoropropyl, perfluorobutyl, phenyl, biphenyl, fluorenyl, fluoranthenyl, terphenyl, pyrenyl, chrysenyl, naphthacenyl, perylene, pyridyl, pyrrolyl, furanyl, thiophenyl, imidazolyl, benzoimidazolyl, quinolyl, triazinyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, pyrazolyl, indolyl, carbazolyl, thiazolyl, oxazolyl, benzothiazolyl, benzoxazolyl, phenanthrolinyl, quinoxalinyl or N-carbazolyl;

R₁ to R₄ each independently represent hydrogen, deuterium, chloro, fluoro, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, decyl, dodecyl, hexadecyl, trifluoromethyl, perfluoroethyl, trifluoroethyl, perfluoropropyl, perfluorobutyl, phenyl, biphenyl, fluorenyl, fluoranthenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, perylenyl, pyridyl, pyrrolyl, furanyl, thiophenyl, imidazolyl, benzoimidazolyl, indenyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinolyl, triazinyl, benzofuranyl, dibenzofuranyl, benzothiophenyl, dibenzothiophenyl, pyrazolyl, indolyl, carbazolyl, thiazolyl, oxazolyl, benzothiazolyl, benzoxazolyl, phenanthrolinyl or N-carbazolyl;

a to d each independently represent an integer of 1 to 2; and

L₁, L₂, Ar₁, Ar₂, R’, R₁ to R₄, R₂₁ and R₂₂ each independently may be further substituted with at least one selected from the group consisting of deuterium, chloro, fluoro, methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, t-butyl, n-pentyl, i-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, decyl, dodecyl, hexadecyl, trifluoromethyl, perfluoroethyl, trifluoroethyl, perfluoropropyl, perfluorobutyl, phenyl, biphenyl, fluorenyl, fluoranthenyl, triphenylenyl, pyrenyl, chrysenyl, naphthacenyl, perylenyl, fluorotrimethylsilyl, triethylsilyl, tripropylsilyl, tri(t-butyl)silyl, t-butyldimethylsilyl, dimethylphenylsilyl, carbazolyl and triphenylsilyl.
The organic electroluminescent compound according to claim 1, wherein the compound is selected from the group consisting of:
An organic electroluminescent device comprising the organic electroluminescent compound according to claim 1.