KR100994765B1 - Organic electroluminescent device comprising fluorene-based light emitting material - Google Patents

Abstract

The present invention relates to an organic electroluminescent device comprising a novel fluorene-based light emitting material. The organic light emitting display device according to the present invention has a low driving voltage, high luminous efficiency and color purity, and excellent life characteristics.

Description

Organic electroluminescent device comprising fluorene-based light emitting material {ORGANIC ELECTROLUMINESCENT DEVICE COMPRISING FLUORENE-BASED LIGHT EMITTING MATERIAL}

The present invention relates to an organic electroluminescent device comprising a novel fluorene-based light emitting material.

Recently, an organic light emitting device capable of low-voltage driving with a self-luminous type has superior viewing angles, contrast ratios, and the like, and is lighter and thinner than a liquid crystal display (LCD), which is a mainstream of flat panel display devices. It is also attracting attention as a next-generation display device because it is advantageous in terms of power consumption and has a wide range of color reproduction.

In general, an organic light emitting display device has a structure including a cathode (electron injection electrode), an anode (hole injection electrode), and an organic layer between the two electrodes. In this case, the organic layer may include a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL), or an electron injection layer (EIL) in addition to the light emitting layer (EML). , an electron injection layer, and may further include an electron blocking layer (EBL) or a hole blocking layer (HBL) due to light emission characteristics of the light emitting layer. In general, an organic light emitting display device has a structure in which an anode, a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and a cathode are stacked in this order.

When an electric field is applied to the organic light emitting device having such a structure, holes are injected from the anode, electrons are injected from the cathode, and holes and electrons are recombined in the emission layer through the hole transport layer and the electron transport layer, respectively. Form luminescence excitons. The formed light exciton emits light as it transitions to ground states. In order to increase the efficiency and stability of the light emitting state, a light emitting dye (dopant) may be doped into the light emitting layer (host).

As the material used for the organic layer of the organic light emitting device, an arylamine-based compound including a fluorene structure is variously known.

[Document 1] JP 2005-325097 (Konica) November 24, 2005.

[Reference 2] JP 3,884,557 (Mitsui Chem INC) November 30, 2006.

[Reference 3] JP 3,902,993 (Konica) January 12, 2007.

Document 4 JP 2007-063285 (Konica) March 15, 2007.

[Reference 5] JP 2007-137795 (Tosoh Corporation) June 7, 2007

[Document 6] JP 2007-142011 (Tosoh Corporation) June 7, 2007

[Document 7] JP 3,983,215 (Mitsui Chem INC) 2007. 7. 13.

[Document 8] JP 2007-191465 (Konica) August 8, 2007

Document 9 JP 4,059,834 (Mitsui Chem INC) 2007. 12. 28.

Document 10 JP 2008-050337 (Tosoh Corporation) March 6, 2008

However, in the case of an organic light emitting device using an arylamine-based compound including a known fluorene structure as a light emitting layer material, there are many difficulties in practical use due to high driving voltage, low luminous efficiency and short lifespan. Accordingly, efforts have been made to develop organic light emitting diodes having low voltage driving, high efficiency, and long lifetime using various kinds of light emitting layer materials having an arylamine-based structure including a fluorene structure.

Accordingly, it is an object of the present invention to provide an organic electroluminescent device in which a fluorene-based light emitting material having excellent light emitting ability is included in a light emitting layer, and driving voltage, light emission efficiency, and lifespan characteristics are remarkably improved.

In order to achieve the above object, the present invention provides an organic light emitting device comprising the compound of formula (I):

[Formula I]

Where

R ₁ to Each R ₉ is independently hydrogen; Of C _{1-30 with} or without one or more heteroatoms selected from the group consisting of S, N, O, P and Si Alkyl or cycloalkyl groups; Of C _{1-10 with} or without one or more heteroatoms selected from the group consisting of S, N, O, P and Si Aryl groups substituted with alkyl, alkenyl, cycloalkyl, arylalkyl, aryloxy groups; And C _5-30 containing or not containing at least one hetero atom selected from the group consisting of S, N, O, P and Si. An aryl group, wherein R ₁ to R ₉ may be substituted or unsubstituted with F or Cl, and also R ₁ and R ₂ , R ₃ and With R ₄ , R ₅ With R ₆ , and R ₇ One or more of R ₈ may combine with each other to form one or more rings,

Each R ₁₀ is independently hydrogen; Of C _{1-30 with} or without one or more heteroatoms selected from the group consisting of S, N, O, P and Si Alkyl groups; Or C _1-30 containing or without one or more hetero atoms selected from the group consisting of S, N, O, P and Si It may be a C _5-30 aryl group unsubstituted or substituted with an alkyl group, or may be fused with a phenyl to which it is bonded to form a polycyclic aromatic compound.

The organic electroluminescent device according to the present invention has a low driving voltage, high luminous efficiency and color purity, and excellent lifespan characteristics by including a fluorene-based light emitting material having excellent luminous ability in the light emitting layer.

The organic light emitting display device according to the present invention has a structure in which a substrate, an anode (hole injection electrode), a light emitting layer (EML), and a cathode (electron injection electrode) are sequentially stacked. In this case, a hole injection layer (HIL) and a hole transport layer (HTL) may be additionally included between the anode and the light emitting layer, and an electron injection layer (EIL), an electron transport layer (ETL), etc. may be additionally included between the cathode and the light emitting layer. In addition, a hole blocking layer (HBL) and an electron blocking layer (EBL) may be further included. Preferably, the electron blocking layer EBL may be included between the anode and the light emitting layer, and the electron transport layer ETL, the electron injection layer EIL, or the hole blocking layer HBL may be included between the cathode and the light emitting layer (FIG. 1). Reference).

The organic light emitting display device according to the present invention includes the light emitting material of Chemical Formula 1 in the light emitting layer and, optionally, the electron transport layer.

Formula I

Where

R ₁ to Each R ₉ is independently hydrogen; Of C _{1-30 with} or without one or more heteroatoms selected from the group consisting of S, N, O, P and Si Alkyl or cycloalkyl groups; Of C _{1-10 with} or without one or more heteroatoms selected from the group consisting of S, N, O, P and Si Aryl groups substituted with alkyl, alkenyl, cycloalkyl groups, arylalkyl or aryloxy groups; And C _5-30 containing or not containing at least one hetero atom selected from the group consisting of S, N, O, P and Si. An aryl group, wherein R ₁ to R ₉ may be substituted or unsubstituted with F or Cl, and also R ₁ and R ₂ , R ₃ and With R ₄ , R ₅ With R ₆ , and R ₇ One or more of R ₈ may combine with each other to form one or more rings,

Each R ₁₀ is independently hydrogen; Of C _{1-30 with} or without one or more heteroatoms selected from the group consisting of S, N, O, P and Si Alkyl groups; Or C _1-30 containing or without one or more hetero atoms selected from the group consisting of S, N, O, P and Si It may be a C _5-30 aryl group unsubstituted or substituted with an alkyl group, or may be fused with a phenyl to which it is bonded to form a polycyclic aromatic compound.

Preferably, in the above formula R ₁ to Each R ₉ is independently hydrogen, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, neopentyl, hexyl, heptyl, octyl, trichloromethyl, trifluoromethyl, Triphenylmethyl, cyclopentyl, cyclohexyl, phenyl, 2-phenylisopropyl, styryl, benzyl, α-phenoxybenzyl, α, α-dimethylbenzyl, α, α-phenylmethylbenzyl, α, α-di Trifluoromethylbenzyl, α, α-benzyloxybenzyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 1-naphthyl, 2-naphthyl, 5-methylnaphthyl, biphenyl, 4-methylbiphenyl, 4-ethylbiphenyl, 4-cyclohexylbiphenyl, terphenyl, 3,5-dichlorophenyl, anthryl, pyrenyl, and the like, wherein R ₁ and R ₂ , R ₃ and With R ₄ , R ₅ With R ₆ , and R ₇ One or more of R ₈ may be bonded to each other to form a ring, and each R ₁₀ is independently hydrogen, methyl, ethyl, propyl, or phenyl, or 1-naphthyl, 2-naphthyl together with phenyl to which it is bonded Etc. can be formed.

Most preferably, R ₁ and R ₂ are each independently methyl, ethyl, propyl, cyclopentyl, cyclohexyl, phenyl or methylphenyl, or R ₁ and R ₂ may combine with each other to form fluorenyl; R ₃ to R ₉ are hydrogen; R ₁₀ may be hydrogen or phenyl or may form 1-naphthyl or 2-naphthyl with the phenyl to which it is attached.

Specific examples of the compound represented by Formula (I) include, but are not limited to, compounds of Formulas 1 to 32.

The compound of formula (I) may be prepared by the Buchwald-Hartwig amine reaction of the aromatic amine compound and the aromatic halogen compound in the carbon-nitrogen coupling reaction. For example, the compound of Formula I may be prepared by the method as shown in Scheme 1 below.

Where

R ₁ to R ₁₀ are as defined above,

X is a halogen atom, preferably I or Br.

Hereinafter, the organic light emitting display device of the present invention will be described in detail.

The organic light emitting display device according to the present invention may be manufactured by the following process.

First, a positive electrode is formed by coating a positive electrode material on a substrate in a conventional manner. The substrate is not limited as long as it is a material having excellent transparency, surface smoothness, ease of handling and waterproofness, and for example, a glass substrate or a transparent plastic substrate is preferable. In addition, as the anode material, indium tin oxide (ITO), indium zinc oxide (IZO), tin oxide (SnO ₂ ), zinc oxide (ZnO), and the like, which are transparent and have excellent conductivity, may be used.

Subsequently, the hole injection layer (HIL) material is vacuum-deposited or spin-coated on the anode in a conventional manner to form a hole injection layer. The hole injection layer material is not particularly limited, for example, copper phthalocyanine (CuPc), 4,4 ', 4 "-tris (3-methylphenylamino) triphenylamine (m-MTDATA), 4,4', 4"- 4,4 ', 4 "-tri (N-carbazolyl) triphenylamine (TCTA), 4,4' which is tris (3-methylphenylamino) phenoxybenzene (m-MTDAPB) and starburst amines , 4 "-tris (N- (2-naphthyl) -N-phenylamino) -triphenylamine (2T-NATA), N, N'-di-1-naphthyl- commercially available from Idemitsu N, N'-bis ((4-diphenylamino) phenyl) benzidine (IDE406) or the like may be used as the hole injection layer material.

Subsequently, a hole transport layer is formed on the hole injection layer by vacuum thermal evaporation or spin coating of a hole transport layer (HTL) material in a conventional manner. The hole transport layer material is not particularly limited, and bis (N- (1-naphthyl-n-phenyl)) benzidine (α-NPD), N, N'-di (naphthalen-1-yl) -N, N ' Diphenyl-benzidine (NPB), N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine (TPD), etc. Can be used as a substance.

Subsequently, the light emitting layer (EML) material is vacuum-heat-deposited or spin-coated on the hole transport layer in a conventional manner to form the light emitting layer. The light emitting layer material includes a host material and a dopant. The host material is not particularly limited, and for example, tris (8-quinolinolato) aluminum (Alq ₃ ) and the like can be used. As the dopant, the compound of Formula I may be used, and the host material and the compound of Formula I may be used in a molar ratio of 99.9: 0.1 to 70:30. It is also possible to further use conventional fluorescent or phosphorescent dopants with the compounds of formula (I). The fluorescent dopant and phosphorescent dopant are not particularly limited. For example, the fluorescent dopant is IDE102, IDE105, or C-545T ("2,3,6,7-tetra as a green fluorescent dopant) available from Idemitsu. Hydro-1,1,7,7-tetramethyl-1H, 5H, 11H-10- (2-benzothiazolyl) quinolizino- [9,9a, 1gh] coumarin ") and tris () as a phosphorescent dopant 2-phenylpyridine) iridium (III) (Ir (ppy) ₃ ), iridium (III) bis [(4,6-difluorophenyl) pyridinato-N, C-2 '] picolinate (FIrpic) (Chihaya Adachi etc. Appl. Phys . Lett ., 2001 , 79 , 3082-3084), platinum (II) octaethylporphyrin (PtOEP), TBE002 (Kobiion) and the like can be used.

Subsequently, an electron transport layer is formed on the light emitting layer by vacuum thermal evaporation or spin coating of an electron transport layer (ETL) material in a conventional manner. According to the present invention, the electron transport layer material is not particularly limited. For example, tris (8-quinolinolato) aluminum (Alq ₃ ), or the like may be used, or the compound of formula (I) may be further used.

Optionally, (8-quinolinolato) lithium (Liq), bis (8-hydroxy-2-methylquinolinolato) -aluminum biphenoxide (BAlq), basthocuproine (BCP), Vacuum thermal deposition and spin coating of a hole blocking layer (HBL) material, such as LiF, to form a hole blocking layer between the light emitting layer and the electron transport layer in a conventional manner, and by using a phosphorescent dopant in the light emitting layer, triplet excitons or holes The phenomenon of diffusion into the electron transport layer can be prevented.

Subsequently, an electron injection layer is formed on the electron transport layer by vacuum thermal evaporation or spin coating of an electron injection layer (EIL) material in a conventional manner. The electron injection layer material is not particularly limited, and materials such as LiF, Liq, Li ₂ O, BaO, NaCl, CsF, and the like may be used.

Finally, the cathode material is vacuum-deposited on the electron injection layer by a conventional method to form a cathode. The negative electrode material may be lithium (Li), aluminum (Al), aluminum-lithium (Al-Li), calcium (Ca), magnesium (Mg), magnesium-indium (Mg-In), magnesium-silver (Mg- Ag) and the like can be used. In addition, in the case of a top emission organic field device, a transparent cathode through which light may pass may be formed using ITO or IZO.

The organic light emitting display device according to the present invention may be manufactured in the same order as described above, that is, in the order of anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / anode. The electron injection layer, the electron transport layer, the hole blocking layer, the light emitting layer, the hole transport layer, the hole injection layer and the anode may be manufactured in the order.

Hereinafter, the present invention will be described in more detail with reference to Preparation Examples and Examples. However, the following examples are only for illustrating the present invention and do not limit the present invention.

Production Example  1: compound of formula 9 [ N ⁴ , N ^4' - Vis (9,9- Diphenyl -9H- Fluorene -2 days)- N ⁴ , N ^4' -Di (naphthalen-1-yl) -1,1'- Binaphthyl -4,4'- Diamine Synthesis

1,1'-dibromobinaphthalene (10 mmol, 4.1 g), N- (naphthalen-2-yl) -9,9-diphenyl-9H-flu after filling a 1000 ml three-necked round bottom flask with nitrogen Oren-2-amine (22 mmol, 10.1 g), Pd ₂ (dba) ₃ (0.5 mmol, 0.5 g), P ( t- Bu) ₃ (0.5 mmol, 0.05 g), t- BuONa (2.1 g, 22 mmol) was added and 500 ml of toluene was added thereto as a solvent. The resulting mixture was stirred at 120 ° C. for 6 hours, then the temperature of the reaction product was cooled to room temperature and extracted with dichloromethane. The obtained extract was dried over anhydrous magnesium sulfate and fractional distillation to remove the solvent. The obtained residue was separated by silica gel column chromatography (eluent-dichloromethane: n-hexane = 1: 5) to give 7.8 g of the title compound as a yellow solid.

Yield: 67% (7.8 g)

FD-MS: m / z = 1169 (C ₉₀ H ₆₀ N ₂ = 1169.45)

¹ H-NMR (CDCl ₃ , 400 MHz) δ (ppm) 7.84 (d, 2H), 7.69-7.52 (m, 12H), 7.35-7.25 (m, 14H), 7.20-7.01 (m, 24H), 6.75 ( s, 2H), 6.69-6.51 (m, 6H).

Production Example  2: compound of formula 30 [ N ⁴ , N ^4' - Vis (9,9-dimethyl-9H- Fluorene -2 days)- N ⁴ , N ^4' -D Biphenyl -1-yl) -1,1'- Binaphthyl -4,4'- Diamine Synthesis

Into a 1000 ml three-necked round bottom flask with nitrogen, 1,1'-dibromobinaphthalene (10 mmol, 4.1 g), N- (biphenyl-1-yl) -9,9-dimethyl-9H- Fluorene-2-amine (22 mmol, 8.0 g), Pd ₂ (dba) ₃ (0.5 mmol, 0.5 g), P ( t- Bu) ₃ (0.5 mmol, 0.05 g), t- BuONa (2.1 g, 22 mmol) was added and 500 ml of toluene was added thereto as a solvent. The resulting mixture was stirred at 120 ° C. for 6 hours, then the temperature of the reaction product was cooled to room temperature and extracted with dichloromethane. The obtained extract was dried over anhydrous magnesium sulfate and fractional distillation to remove the solvent. The obtained residue was separated by silica gel column chromatography (eluent-dichloromethane: n-hexane = 1: 5) to give 7.0 g of the title compound as a yellow solid.

Yield: 72% (7.0 g)

FD-MS: m / z = 975 (C ₇₄ H ₅₈ N ₂ = 975.27)

¹ H-NMR (CDCl ₃ , 400 MHz) δ (ppm) 7.81 (d, 2H), 7.70-7.43 (m, 12H), 7.40-7.13 (m, 20H), 6.72 (s, 2H), 6.64-6.49 ( m, 8H), 1.72 (s, 12H).

Example  1, 2 and Comparative example  : Of organic light emitting device Performance test

Using the compound of Formula 9 (Compound 9) and the compound of Formula 30 (Compound 9) obtained in Preparation Example 1 and Preparation Example 2 as a light emitting layer doping material, an organic light emitting display device was manufactured according to the following method. First, a 600 Å hole injection layer (hole injection layer material: 2T-NATA), a 300 Å hole transport layer (hole transport layer material: NPB), and a 450 Å thick compound on the ITO layer (anode) formed on the glass substrate. 9 or compound 30 doped with a 7% doped light emitting layer (luminescent host material: tris (8-quinolinolato) aluminum (Alq ₃ )), an electron transport layer having a thickness of 250 kHz (electron transport layer material: tris (8-quinolinolato) Alumina (Alq ₃ )), an electron injection layer (electron injection layer material: LiF) having a thickness of 10 kHz and an aluminum cathode having a thickness of 1500 Å were sequentially deposited to manufacture an organic light emitting display device.

As a comparative example, 2,3,6,7-tetrahydro-1,1,7,7-tetramethyl-1H, 5H, 11H-10- (2-benzothiazolyl) quinolizino instead of the compound of the present invention -[9,9a, 1gh] coumarin (C-545T) was used as a light emitting layer doping material (in this case, tris (8-quinolinolato) aluminum (Alq ₃ ) is used as the light emitting host material). An organic electroluminescent device was manufactured.

The performance of the organic light emitting diodes manufactured in Examples 1 and 2 and Comparative Examples were evaluated. As a result, the luminous efficiency and color coordinates are shown in Table 1 below, and the voltage-luminance, current density-luminance, and voltage-current The density, luminous efficiency-luminance and power efficiency-luminance curves are shown in FIGS. 2-6, the x and y color coordinate (CIE) -luminance curves are shown in FIGS. 7 and 8, the electroluminescence spectrum is shown in FIG. 10 is shown respectively.

-Measured at 4,000 nits

As can be seen from Table 1 and the results of FIGS. 2 to 9, the organic light emitting diodes of Examples 1 and 2 using the compounds 9 and 30 of the present invention in the light emitting layer, the organic light emitting diode using C-545T as a comparative example in the light emitting layer Compared with the low driving voltage, excellent electrical stability, high luminous efficiency and luminous luminance, high color purity and high life characteristics, which are the most important in the organic light emitting device.

1 is a schematic diagram showing the structure of a general organic electroluminescent device,

2 is a voltage-luminance curve of the compound represented by Compounds 9 and 30 of the present invention for the organic light emitting device manufactured,

3 is a current density-luminance curve of the compounds represented by Compounds 9 and 30 of the present invention for the prepared organic electroluminescent device,

4 is a voltage-current density curve of compounds represented by compounds 9 and 30 of the present invention for the organic light emitting device manufactured,

5 is a light emission efficiency-luminance curve of the compounds represented by the compounds 9 and 30 of the present invention for the organic light emitting device manufactured,

6 is a power efficiency-luminance curve of the compounds represented by the compounds 9 and 30 of the present invention for the organic light emitting device manufactured,

7 is a x color coordinate-luminance curve of the compound represented by Compounds 9 and 30 of the present invention with respect to the manufactured organic electroluminescent device,

8 is a y color coordinate-luminance curve of the compound represented by Compounds 9 and 30 of the present invention with respect to the manufactured organic electroluminescent device,

9 is an electroluminescence spectrum of the compounds represented by Compounds 9 and 30 of the present invention for the organic electroluminescent device manufactured,

10 is a life curve of the compounds represented by the compounds 9 and 30 of the present invention for the organic light emitting device manufactured.

Claims (13)

An organic electroluminescent device comprising a light emitting layer disposed between an anode and a cathode, wherein the light emitting layer contains a compound of formula (I) In this case, the compound of formula I, characterized in that selected from the group consisting of the compound of formula 1 to 32, an organic light emitting device: Formula I

Where R ₁ and R ₂ are each independently methyl, cyclopentyl, cyclohexyl, phenyl or methylphenyl, or R ₁ and R ₂ may combine with each other to form fluorenyl; R ₃ to R ₉ are hydrogen; R ₁₀ is hydrogen or phenyl or together with the phenyl to which it is attached forms 1-naphthyl or 2-naphthyl;

delete delete delete The method of claim 1, An organic light emitting display device, wherein the compound of Formula I is a compound of Formula 9 or 30:

The method according to claim 1 or 5, An organic electroluminescent device having an organic electroluminescent device having a structure of an anode / hole injection layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode. The method of claim 6, An organic electroluminescent device, wherein the light emitting layer further contains tris (8-quinolinolato) aluminum (Alq ₃ ) as a host material. The method of claim 7, wherein The molar ratio of the host material and the compound of formula I is 99.9: 0.1 to 70:30, organic light emitting device. The method of claim 6, Hole injection layer is copper phthalocyanine (CuPc), 4,4 ', 4 "-tris (3-methylphenylamino) triphenylamine (m-MTDATA), 4,4', 4" -tris (3-methylphenylamino) phenoxy Cybenzene (m-MTDAPB), 4,4 ', 4 "-tri (N-carbazolyl) triphenylamine (TCTA) and 4,4', 4" -tris (N- (2-naphthyl) -N An organic electroluminescent device containing a material selected from the group consisting of -phenylamino) -triphenylamine (2T-NATA). The method of claim 6, The hole transport layer is bis (N- (1-naphthyl-n-phenyl)) benzidine (α-NPD), N, N'-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (NPB ) And N, N'-diphenyl-N, N'-bis (3-methylphenyl) -1,1'-diphenyl-4,4'-diamine (TPD) Electroluminescent element. The method of claim 6, An organic electroluminescent device, wherein the electron transport layer contains tris (8-quinolinolato) aluminum. The method of claim 6, An organic electroluminescent device, wherein the compound of formula I is also included in the electron transport layer. The method of claim 6, The electron injection layer contains a material selected from the group consisting of LiF, Liq, Li ₂ O, BaO, NaCl and CsF, organic light emitting device.

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