KR20080061800A - Dibenzofuran compounds, materials comprising the same for organic electroluminescent device, and organic electroluminescent device - Google Patents

Abstract

Dibenzofuran compounds are provided to improve thermal stability and luminescence properties by introducing a silane group expressing steric hindrance properties for preventing excimer and exciplex and anthracene group and dibenzofuran having enhanced electron transfer properties, so that the efficiency and color purity are improved and driving voltage is lowered in an organic electroluminescent device. The dibenzofuran compounds represented by the formula(1) show improved thermal stability and luminescence properties, wherein l is 1 or 2, n is an integer from 0 to 2, m is an integer from 0 to 2, p is 1 or 2, j is an integer from 1 to 4 and k is an integer from 1 to 4; Ar1, Ar2 and Ar3 are each independently optionally substituted C6-C20 arylene group; and R1 and R2 are each independently hydrogen, C1-C20 linear, non-linear and cyclic alkyl group, C1-20 alkoxy group, aryloxy group, halogen atom, cyano group, nitro group, trifluoro group or methyl group. An organic electroluminescent material contains the dibenzofuran compounds represented by the formula(1). An organic electroluminescent device contains a cathode, an anode and a luminescent layer containing the organic electroluminescent material with the dibenzofuran compounds represented by the formula(1).

Description

Dibenzofuran Compounds, Materials Comprising The Same For Organic Electroluminescent Device, and Organic Electroluminescent Device

1 is a schematic cross-sectional view of an organic light emitting diode (OLED) according to an embodiment of the present invention;

2 is a UV and PL spectrum of the solution state using the compound 1 according to Synthesis Example 5 of the present invention,

3 is a view showing color coordinates of an emission spectrum of a solution state using Compound 1 according to Synthesis Example 5 of the present invention.

Brief description of the main symbols in the drawing

1: Substrate # 2: Anode

3: hole injection layer: 4: hole transport layer

5: light emitting layer 6: electron transport layer

7: negative electrode 8: power supply

The present invention relates to a dibenzofuran compound, an organic electroluminescent device material comprising the same, and an organic electroluminescent device.

Liquid crystal display (LCD), which is the most widely used at present, is a non-light emitting display device, which consumes little power and is light. However, the device driving system is complicated and characteristics such as response time and contrast are not satisfactory. Therefore, researches on organic electroluminescent devices, which are recently attracting attention as the next-generation flat panel displays, are being actively conducted. The organic electroluminescent device is a self-luminous device and has many advantages such as brightness, driving voltage and response speed and no viewing angle dependence compared to the liquid crystal display.

The light emitting mechanism of the organic electroluminescent device is as follows. Holes injected from the anode into the valence band or highest occupied molecular orbital (HOMO) of the hole injection layer (HIL) proceed to the emitting layer through the hole transporting layer (HTL). At the same time, electrons move from the cathode to the emission layer through the electron injection layer to combine with holes to form excitons. The exciton falls to the ground and emits light.

Using the principle of the organic electroluminescent device described above, Eastman Kodak Co., Ltd. in 1987 used TPD (N-N'-DiphenyI-N-N'-bis (methylphenyl-1,1'-biphenyl) as a hole transporting layer. An organic electroluminescent device using Alq3 (tris (8-hydroxy-quinoline) aluminum complex) as -4,4'-diamine) was developed.

Blue is doped with a blue dopant to the blue host, and implemented using Alq3 as the electron transport layer (ETL), Alq3 may be omitted depending on the characteristics of the blue host.

In addition, as a blue light emitting material, the central portion has a diphenylanthracene structure, a light emitting compound in which an aryl group is substituted at the terminal, an anthracene compound derivative, 9,10-di (2-naphthyl) anthracene (9,10-Di (2) -naphthyl) anthracene (ADN) is being studied.

In the case of configuring the display device using the organic electroluminescent device, it is one of the most important problems to ensure the long life and reliability of the organic electroluminescent device. However, such conventional anthracene derivatives do not have excellent film forming processability, such as difficulty in forming a uniform thin film, do not have excellent heat resistance, and due to the plate-like structure, aggregation between molecules occurs during deposition, resulting in high efficiency and high quality. There is a problem that can not emit blue light.

These various blue light emitting compounds have been known to have excellent luminescence properties, but due to their physical and chemical changes, photochemical and electrochemical changes, peeling and melting, crystallization and pyrolysis, they are still applied to organic electroluminescent devices. It is difficult to satisfy high brightness and long life at the same time at low voltage, and there are problems of low storage durability and reliability of the device. Due to these problems, there are many difficulties in commercializing the above-described compounds in organic light emitting devices, and there are limitations in the application to various displays.

Therefore, there is a need for the development of new compounds and organic electroluminescent devices using the same that can overcome the above problems.

The present invention is to solve the above problems,

The objective of this invention is to synthesize silane compounds that exhibit thermal stability and excimer that inhibit luminescent properties, and sterically hindered properties to prevent exciplex, and anthracene groups having excellent electron transport properties and dibenzofuran.

In addition, an object of the present invention is to provide an organic electroluminescent device having high efficiency, high color purity, low driving voltage by applying the synthesized compound as a light emitting layer material.

The present invention for achieving the above object,

It provides a dibenzofuran compound represented by the formula (1).

[Formula 1]

Wherein j, k, l, m, n, and p are integers, l is 1 to 2, n is 0 to 2, m is 0 to 2, p is 1 to 2, j is 1 to 4, k Is 1 to 4,

Ar1, Ar2, and Ar3 are each independently and the same or different (when l, m, n are 2, each independently and the same or different for Ar1, Ar2, and Ar3), an arylene group having 6 to 20 carbon atoms, with or without substituents Is,

R1 and R2 are selected from hydrogen, linear, nonlinear, and cyclic alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aryloxy groups, halogen atoms, cyano groups, nitro groups, and trifluoromethyl groups, j And k are each 2 or more, the same or different independently from each other.)

In addition, Ar1, Ar2, and Ar3 may have a substituent at a hydrogen position, and as a substituent, independently of each other, a halogen atom (fluorine, chlorine, bromine, iodine), a nitro group, an alkyl group having 1 to 20 carbon atoms, and having 6 to 20 carbon atoms Provided is a dibenzofuran compound characterized by being selected from the group consisting of a cycloalkyl group, an alkoxy group having 1 to 20 carbon atoms, a cyano group, and a trifluoromethyl group.

In addition, preferred examples of? Ar1, Ar2, and Ar3 of the compound and specific examples of the dibenzofuran compound of Formula 1 are given.

The present invention also provides a material for an organic electroluminescent device comprising the dibenzofuran compound described above.

The present invention also provides an organic electroluminescent device having a plurality of organic compound layers including an anode, a cathode, and a light emitting layer positioned between the anode and the cathode, wherein the dibenzofuran compound is partially or partially disposed on the plurality of organic compound layers. It provides an organic electroluminescent device characterized in that it contains.

The organic compound layer may include at least one of a light emitting layer, an electron injection layer, and an electron transport layer, and the compound may be included in at least one of the light emitting layer, the electron injection layer, and the electron transport layer. .

Hereinafter, the present invention will be described in more detail. The following detailed description illustrates the present invention by way of example, and the present invention is not limited thereto.

Dibenzofuran compound according to the invention is characterized in that represented by the formula (1).

[Formula 1]

Wherein j, k, l, m, n, and p are integers, l is 1 to 2, n is 0 to 2, m is 0 to 2, p is 1 to 2, j is 1 to 4, k Is 1 to 4.

Ar1, Ar2, and Ar3 are each independently and the same or different (when l, m, n is 2, they are independent and the same or different for each of Ar1, Ar2, and Ar3, ie, the same Ar1 may be different from each other. ) And an arylene group having 6 to 20 carbon atoms with or without a substituent.

R1 and R2 are selected from hydrogen, linear, nonlinear, and cyclic alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aryloxy groups, halogen atoms, cyano groups, nitro groups, and trifluoromethyl groups, j And k are each 2 or more, the same or different independently from each other.

In addition, Ar1, Ar2, and Ar3 may have a substituent at a hydrogen position, and as a substituent, independently of each other, a halogen atom (fluorine, chlorine, bromine, iodine), a nitro group, an alkyl group having 1 to 20 carbon atoms, and having 6 to 20 carbon atoms It may be selected from the group consisting of a cycloalkyl group, an alkoxy group having 1 to 20 carbon atoms, a cyano group, and a trifluoromethyl group.

Preferred specific examples of Ar1, Ar2, and Ar3 include the following Chemical Formulas 2 to 9.

In the following formulas (2) to (9), the solid lines representing the bonding positions are drawn through all the rings constituting the polymembered ring, respectively, which means that the bonding positions of Ar1 and Ar2, Ar2 and anthracene, Ar3 and dibenzofuran are either Position means good.

Hereinafter, although the specific example of the dibenzofuran type compound represented by General formula (1) of this invention is shown, this invention is not limited to these exemplary compounds.

Hereinafter, an organic electroluminescent device material and an organic electroluminescent device according to the present invention will be described.

The present invention provides a material for an organic electroluminescent device comprising the dibenzofuran compound of the formula (1). Any material for an organic electroluminescent device containing the dibenzofuran compound of Formula 1 is included in the present invention. Materials for organic electroluminescent devices are well known in the art, so detailed descriptions are omitted (but an example is given in the description of the organic electroluminescent devices of the present invention), and these are mixed with a dibenzofuran compound of Formula 1 It may be made and included in the present invention.

The organic electroluminescent device according to the present invention is an organic electroluminescent device having a plurality of organic compound layers including an anode, a cathode, and a light emitting layer positioned between the anode and the cathode. It is characterized in that it is contained in all or part of the plurality of organic compound layers. The organic compound layer may include at least one of a light emitting layer, an electron injection layer, and an electron transport layer, and the organic silane compound may be contained in at least one of the light emitting layer, the electron injection layer, and the electron transport layer.

A more specific example is described as follows.

1 is a cross-sectional view of an organic electroluminescent device according to an embodiment of the present invention. As illustrated, the substrate 1, the anode 2, the hole transport layer 4, the light emitting layer 5, the electron transport layer 6, and the cathode 7 may be provided. It may further include an electron injection layer (not shown) between the electron transport layer and the cathode, and a hole injection layer 3 between the anode and the hole transport layer.

The organic compound layer refers to a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and the like, and all or part thereof includes the dibenzofuran compound of Formula 1 above.

Examples of the anode (2) material include metal oxides or metal nitrides such as ITO, IZO, tin oxide, zinc oxide, zinc aluminum oxide, and titanium nitride; Metals such as gold, platinum, silver, copper, aluminum, nickel, cobalt, lead, molybdenum, tungsten, tantalum and niobium; Alloys of these metals or alloys of copper iodides; Conductive polymers such as polyaniline, polythiopine, polypyrrole, polyphenylenevinylene, poly (3-methylthiopine), and polyphenylenesulfagard. The anode 2 may be formed of only one type of the aforementioned materials or may be formed of a mixture of a plurality of materials. In addition, a multilayer structure composed of a plurality of layers of the same composition or different compositions can be formed.

The hole injection layer 3 of the present invention may use materials known in the art, but is not limited to PEDOT / PSS or copper phthalocyanine (CuPc), 4,4 ', 4 "-tris (3-methylphenylphenylamino) A material such as triphenylamine (m-MTDATA) is formed to a thickness of 5 nm to 40 nm.

The hole transport layer 4 is 4,4'-bis [N- (1-naphthyl) -N-phenyl-amino] -biphenyl (NPD) or N, N'-diphenyl-N, N'-bis Substances such as (3-methylphenyl) -1,1'-biphenyl-4,4'-diamine (TPD) can be used.

The light emitting layer 5 may be a material known in the art, and is not limited thereto, but may be selected from (4,4'-bis (2,2-diphenyl-ethen-1-yl) diphenyl (DPVBi) and bis ( Styryl) amine (DSA), bis (2-methyl-8-quinolinolato) (triphenylsiloxy) aluminum (III) (SAlq), bis (2-methyl-8-quinolinolato) ( Para-phenolato) aluminum (III) (BAlq), bis (salen) zin (II), 1,3-bis [4- (N, N-dimethylamino) phenyl-1,3,4-oxadiazolyl] Benzene (OXD8), 3- (biphenyl-4-yl) -5- (4-dimethylamino) 4- (4-ethylphenyl) -1,2,4-triazole (p-EtTAZ), 3- ( 4-biphenyl) -4-phenyl-5- (4-tert-butylphenyl) -1,2,4-triazole (TAZ), 2,2 ', 7,7'-tetrakis (non-phenyl -4-yl) -9,9'-spirofluorene (Spiro-DPVBI), tris (para-ter-phenyl-4-yl) amine (p-TTA), 5,5-bis (dimethylbutylboryl) -2,2-bithiophene (BMB-2T) and perylene.

Tris (8-quinolinato) aluminum (III) (Alq3), DCM1 (4-dicyanomethylene-2-methyl-6- (para-dimethylaminostyryl) -4H-pyran), DCM2 (4- Dicyanomethylene-2-methyl-6- (zulolidin-4-yl-vinyl) -4H-pyran), DCJT (4- (dicyanomethylene) -2-methyl-6- (1,1,7, 7-tetramethylzulolidil-9-enyl) -4H-pyran), DCJTB (4- (dicyanomethylene) -2-tertbutylbutyl-6- (1,1,7,7-tetramethylzololidyl -9-enyl) -4H-pyran), DCJTI (4-dicyanomethylene) -2-isopropyl-6- (1,1,7,7-tetramethylzulolidil-9-enyl) -4H-pyran ) And nile red, rubrene, etc. can be used as a host or dopant.

Dopants may be omitted or optionally added, but are not limited to those listed as host materials above.

The electron transport layer 6 may include an aryl substituted oxadiazole, aryl-substituted triazole, aryl-substituted phenanthroline, benzoxazole, or benzoxazole compound, for example, 1,3 -Bis (N, Nt-butyl-phenyl) -1,3,4-oxadiazole (OXD-7); 3-phenyl-4- (1'-naphthyl) -5-phenyl-1,2,4-triazole (TAZ); 2,9-dimethyl-4,7-diphenyl-phenanthroline (vasocuproin or BCP); Bis (2- (2-hydroxyphenyl) -benzoxazolate) zinc; Or bis (2- (2-hydroxyphenyl) -benziazolate) zinc; As the electron transporting material, (4-biphenyl) (4-t-butylphenyl) oxadiazole (PDB) and tris (8-quinolinato) aluminum (III) (Alq3) can be used, preferably Tris ( Preference is given to 8-quinolinato) aluminum (III) (Alq3).

The electron injection layer and the cathode 7 may use a material known in the art, but is not limited to LiF as an electron injection layer and a metal having a low work function such as Al, Ca, Mg, Ag or the like may be used as the cathode. And Al is preferred.

Hereinafter, the present invention will be described in more detail through synthesis examples and examples.

The reaction scheme from the starting material of the compound synthesized in the synthesis example is as follows.

<Example>

Synthesis Example 1 Synthesis of Compound A.

4 g (17 mmol) of dibromobenzene was dissolved in ether, the temperature was lowered, n-BuLi was added, and triphenylsilyl chloride was added thereto to react at room temperature. After the reaction was completed, the reaction product was extracted with ether and then the solvent was removed under reduced pressure. The product was separated into a column and then dried by filtration under reduced pressure. 66% yield was obtained.

1 H-NMR (CDCl 3, ppm): 7.54-7.5 (m, Ar-H), 7.45 (Ar-H), 7.40-7.35 (m, Ar-H).

IR (KBr, cm ⁻¹ ): 1568, 1477-1376, 1110, 810, 727, 698.

MS (EI) (calcd for C ₂₄ H ₁₉ BrSi, 414; Found: 414).

Synthesis Example 2 Synthesis of Compound B

Dissolve 8.3 g (20 mol) of 4-bromophenyl-triphenylsilane in THF and lower the temperature to add n-BuLi. Trimethyl borate was added thereto and reacted at room temperature. Poured into diluted hydrochloric acid and stirred for 30 minutes. After extraction with methylene chloride, the solvent was removed under reduced pressure, and the product was separated by column, filtered and dried under reduced pressure to obtain a yield of 50%.

1 H-NMR (CDCl 3): 7.54 (6H, Ar-H), 7.5 (2H, Ar-H), 7.4 (2H, Ar-H), 7.36 (9H, Ar-H), 2.0 (s, 2H, B -(OH) 2).

IR (KBr, cm ⁻¹ ): 1589, 1491, 1374-1277, 829, 725, 695.

MS (EI) (calcd for C ₂₄ H ₂₁ BO ₂ Si, 380.14 found, 381).

Synthesis Example 3 Synthesis of Compound C

Compound B 18.49 g (48.61 mmol), 9-broroanthracene 10 g (38.89 mmol), 250 mL of toluene, 2.247 g (1.945 mmol) tetrakistriphenylphosphine palladium, 146 mL of 2N aqueous sodium carbonate solution in a 500 mL three-neck flask And refluxed at 110 degrees Celsius for 18 hours. After the reaction was completed, the reaction temperature was lowered to room temperature, the organic layer was extracted with distilled water and dichloromethane, dried over MgSO ₄ , the solvent was removed under reduced pressure, and the precipitate was reprecipitated with dichloromethane and normal hexane and filtered. 15.95 g (80%) of the product was obtained after vacuum drying.

MS (EI) (calcd for C ₃₈ H ₂₈ Si, 512.71; Found: 512).

Synthesis Example 4 Synthesis of Compound D

Compound C 24g (46.81mmol), NBS 8.77g (49.27mmol), and 150mL DMF were added to a 250mL three-necked flask, and stirred at room temperature for 4 hours. The resulting solid was filtered and washed sufficiently with 1000mL of methanol. 20.96 g (76%) of compound D was obtained after drying.

MS (EI) (calcd for C ₂₇ H ₁₇ BrN ₂ , 591.61; Found: 591).

Synthesis Example 5 Synthesis of Compound 1

Compound D 8g (13.52mmol), 4-dibenzofuran boronic acid 3.15g (14.87mmol), 100mL of 1,2-dimethoxyethane, 0.781g tetrakistriphenylphosphine palladium under a nitrogen atmosphere in a 250mL three-necked flask mmol) and 51 mL of 2N-sodium carbonate aqueous solution were added and refluxed at 80 ° C. for 12 hours. After the reaction was completed, the resulting precipitate was filtered and washed well with 1000 mL of methanol and 1000 mL of water. The washed solid was completely dissolved using 500 mL of THF, and then insoluble impurities were removed using cellite. Subsequently, the resultant was reprecipitated with 200 mL of THF and 200 mL of n-normal hexane, followed by filtration. 5.5 g (60%) of the product was obtained after vacuum drying.

MS (EI) (calcd for C ₅₀ H ₃₄ OSi, 678.89; Found: 678).

< Example 1  Device Fabrication and Evaluation of Organic Compound 1

After forming an ITO electrode on the glass substrate, and then undergoing UV-ozone cleaning or oxygen plasma cleaning, a phthalocyanine copper complex (CuPc) having a structure of the following Chemical Formula 2-1 as a hole injection layer is deposited to a thickness of 100 Å. I was. NPD (N, N'-bis (naphthalen-1-yl) -N, N'-bis (phenyl) benzidine) having a structure of the following Chemical Formula 2-2 was deposited thereon as a hole transport layer, and then blue. Compound 1 was formed as a light emitting material to form a light emitting layer having a thickness of 300 kHz. As an electron transport layer, Alq3 (tris- (8-hydroxyquinoline) aluminum (III)) having a structure of Chemical Formula 2-3 was vacuum deposited to a thickness of 300 Å. Then, a blue organic electroluminescent device was manufactured by vacuum-depositing an Al: Li layer on the top to form an aluminum / lithium electrode having a thickness of 1000 mW.

[Formula 2-2]

[Formula 2-3]

Comparative Example 1

When the emission layer 5 was formed, the blue organic electroluminescence device was manufactured by the same method as Example 1 except for using ADN having the structure of Chemical Formula 2-4 as the blue light emitting material.

[Formula 2-4]

The equipment used for the Example and the comparative example used EL deposition machine of VTS. Characteristics of the organic electroluminescent device manufactured as described above, namely, driving voltage, color coordinate, and efficiency measuring method are as follows, and the results are shown in Table 1.

As shown in the table, the compound of formula (1) adopting a silane which expresses excimer which inhibits thermal stability and luminescent properties and a sterically hindering characteristic that prevents exciplex and dibenzofuran having excellent electron transporting properties is applied as a light emitting layer material. As a result of manufacturing the electroluminescent device, it can be seen that high efficiency, high color purity, and low driving voltage can be provided.

1) Driving voltage and current density

The change of current density according to the voltage change was measured for the manufactured organic electroluminescent device. In the measurement, the current density and the voltage value flowing through the unit device were measured using a current-voltmeter (Kethley SMU 236) while increasing the current density from 2.5 mA / cm ² to 100 mA / cm ² .

2) color coordinates

The current density of the prepared organic electroluminescent device was measured using a colorimeter (Minolta CS-100A) while increasing the current density by 2.5 mA from 2.5 mA / cm ² to 100 mA / cm ² .

3) efficiency

Luminous efficiency was calculated using the measured luminance and current density.

4) ELmax

Power was supplied from the power supply (Kethley SMU 236) and the wavelength was determined as ELmax at the highest intensity of the spectrum taken from photodiodes (Ocean Optics).

TABLE 1

 Driving voltage (V) Current density (mA / cm ² ) Luminance (cd / m ² )  ELmax (nm) Color coordinates CIE1931 (x, y) Efficiency (cd / A) Example 1 9.8 20 564 448 (0.16, 0.122) 2.82 Comparative Example 1 11.5 20 333 460 (0.187, 0.218) 1.67

According to the present invention, a compound of formula (1) incorporating a silane group that exhibits excimers that inhibit thermal stability and luminescent properties and a sterically hindered property that prevents exciplexes, and an anthracene group having excellent electron transporting properties and dibenzofuran is used as a light emitting layer material. By applying to the electroluminescent device can provide high efficiency, high color purity, low driving voltage.

Claims (7)

Dibenzofuran compound represented by the formula (1). [Formula 1]

Wherein j, k, l, m, n, and p are integers, l is 1 to 2, n is 0 to 2, m is 0 to 2, p is 1 to 2, j is 1 to 4, k Is 1 to 4, Ar1, Ar2, and Ar3 are each independently and the same or different (when l, m, n are 2, each independently and the same or different for Ar1, Ar2, and Ar3), an arylene group having 6 to 20 carbon atoms, with or without substituents Is, R1 and R2 are selected from hydrogen, linear, nonlinear, and cyclic alkyl groups having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon atoms, aryloxy groups, halogen atoms, cyano groups, nitro groups, and trifluoromethyl groups, j And k are each 2 or more, the same or different independently from each other.) According to claim 1, Ar1, Ar2, and Ar3 may have a substituent at the hydrogen position, and as a substituent, independently of each other, a halogen atom (fluorine, chlorine, bromine, iodine), a nitro group, an alkyl group having 1 to 20 carbon atoms, carbon atoms A dibenzofuran compound selected from the group consisting of a cycloalkyl group of 6 to 20, an alkoxy group having 1 to 20 carbon atoms, a cyano group, and a trifluoromethyl group. The dibenzofuran compound according to claim 1, wherein Ar1, Ar2, and Ar3 are selected from the following Chemical Formulas 2 to 9.

(In the following Chemical Formulas 2 to 9, the solid lines representing the bonding positions are drawn through all the rings constituting the polymembered ring, respectively, but the binding positions of Ar1 and Ar2, Ar2 and anthracene, Ar3 and dibenzofuran are among the polycyclic rings). Any location means good.) The dibenzofuran compound according to claim 1, which is any one of the compounds represented by the following Compounds 1 to 18.

An organic electroluminescent device material comprising the dibenzofuran compound according to any one of claims 1 to 4. An organic electroluminescent device comprising a plurality of organic compound layers including an anode, a cathode and a light emitting layer positioned between the anode and the cathode, wherein the dibenzofuran compound of any one of claims 1 to 4 is formed of the plurality of organic compounds. An organic electroluminescent device, characterized in that contained in all or part of the compound layer. The organic electroluminescence device of claim 6, wherein the organic compound layer includes at least one of a light emitting layer, an electron injection layer, and an electron transport layer, and the compound is contained in at least one of the light emitting layer, the electron injection layer, and the electron transport layer. device.

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