KR20050043243A - Red luminescent material and organic electroluminescent device - Google Patents

Abstract

The present invention relates to a new red light emitting material and an organic electroluminescent device comprising the same, and the compound of the present invention exhibits excellent chemical and electrical stability, heat resistance, durability, luminous efficiency, emission luminance and color purity, It can be usefully used as a red light emitting material of.

Description

Red luminescent material and organic electroluminescent device comprising the same

The present invention relates to a new red light emitting material and an organic electroluminescent (EL) device including the same. Specifically, a red light emitting material exhibiting excellent chemical and electrical stability, heat resistance, durability, luminous efficiency, luminous intensity and color purity. And an organic electroluminescent device comprising the same.

Recently, the flat panel display device plays a very important role as a device supporting a highly visual information society based on the Internet, which is rapidly growing. In particular, the organic electroluminescent device (organic EL device) capable of low-voltage driving with a self-luminous type has a superior viewing angle, contrast ratio, and the like, as compared to a liquid crystal display (LCD), which is a mainstream of flat panel display devices, and requires no backlight. Light weight and thinness are possible, and it is advantageous in terms of power consumption. In addition, it is attracting attention as a next generation display device because of its fast response speed, strong external shock, wide usable temperature range, and low manufacturing cost. However, the conventional organic EL device has a high driving voltage and low luminous luminance, luminous efficiency and deterioration characteristics as compared to the inorganic EL device and thus has not been put to practical use.

In 1987, CW Tang et al. Used tri (8-quinolinolato) aluminum (hereinafter abbreviated as Alq ₃ ) as a light emitting layer and an amine compound as a hole injecting layer. The organic EL device (Appl. Phys. Lett., 51, 913 (1987)) in which a thin film containing an organic compound emitting green light was laminated, and a coumarin derivative, 4-dicyanomethylene- in an electron transporting light-emitting layer containing Alq _3- Although a device was developed in which light-emitting materials such as 6- (p-dimethylaminostyryl) -2-methyl-4H-pyran (DCM1) were dispersed (J. Appl. Phys., 65 (9), 3610 (1989)) They are difficult to use practically because of low color purity and poor durability.

In addition, CH Chen et al. Introduces an inert alkyl group substituent, for example, tert-butyl group or isopropyl group, instead of the active methyl group located at C-6 of the pyran moiety to suppress the formation of by-products during the reaction. In addition, it was possible to obtain devices with improved luminance and efficiency (Macromol. Symp., 125, 49 (1997)). However, this light emitting material has a long synthesis and purification step, and has a problem in that it is difficult to synthesize a large amount due to low yield.

Therefore, when the conventional organic EL device is used in a full color display device, there are various problems to be solved, such as improvement of luminous efficiency, stability improvement, full colorization, driving method, and panelization technology. Among them, emission color and color purity Improvement and extension of device life have been pointed out as the biggest problems. Particularly, in the case of red, luminous efficiency of about 3 lm / W is required for full colorization, but currently only about 1 lm / W is reached.

Conventionally, as the red light emitting material having high color purity, organometallic complexes based on europium are widely known (Appl. Phys. Lett., 65 (17), 2124 (1994)), but organic electroluminescent devices using the same There is a problem that the highest luminance is significantly low. Further, Japanese Patent Laid-Open No. 1999-329731 discloses a high luminance red organic electroluminescent device using a specific distyryl compound, and XT Tao et al. Discloses a red pigment 3- molecularly designed based on DCM1 structure. A red organic EL device was disclosed in which (dicyanomethylene) -5,5-dimethyl-1- (4-dimethylamino-styryl) cyclohexene was doped in Alq ₃ (Appl. Phys. Lett., 78 (3)). , 279 (2001)), the color purity does not reach the reference value.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a red light emitting material that exhibits excellent chemical and electrical stability, heat resistance, durability, luminous efficiency, light emission luminance, and color purity, and an organic electroluminescent device including the same.

The present invention to achieve the above technical problem,

It provides a red light emitting material represented by the formula (1).

Wherein R ₁ , R ₂ , R _3, R ₄ , R ₅ , and R ₆ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl having 6 to 36 carbon atoms. Group, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms,

In the above formula, D is an aromatic ring of Formula 2 or 3 or two or more aromatic rings.

R ₇ to R ₁₆ each independently represent a hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 36 carbon atoms, a substituted or unsubstituted hetero atom having 1 to 20 carbon atoms. An alkyl group, a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms, a substituted or unsubstituted amine group having 0 to 20 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms.

Hereinafter, preferred embodiments of the present invention will be described in detail.

According to the present invention, the compound represented by Chemical Formula 1 may include a ketone of Chemical Formula 4 including R ₁ and R ₅ and a maleone nitrile of Chemical Formula 5, wherein two CN groups are introduced at the ketone position through a dehydration condensation reaction. After synthesizing the intermediate of Chemical Formula 6, it may be prepared by subjecting the obtained intermediate to a dehydration condensation reaction with the compound represented by the following Chemical Formula 7 including D, R ₂ and R ₃ .

Wherein R ₁ and R ₂ are as defined above.

Wherein R ₁ and R ₂ are as defined above.

Wherein D, R ₂ and R ₃ are as defined above.

In the above reaction, the first dehydration condensation reaction of Chemical Formulas 4 and 5 preferably uses 2 equivalents of ammonium acetate or triethyl amine / paratoluene sulfonic acid in 0.01 equivalents as the acid-base catalyst, and the reaction temperature is 30 to 150 ^o. The reaction is carried out between C, the reaction temperature is preferably carried out for 1 to 72 hours. The reaction solvent is methanol, ethanol, CH ₂ Cl ₂ , acetonitrile, DMF, and the like. The second dehydration condensation reaction between the compounds of formulas 6 and 7 is carried out using a secondary or tertiary amine as a catalyst. Is 0.1 equivalent to 10 equivalents, the reaction temperature is between 30 and 150 ^o C, the reaction temperature is preferably carried out for 1 to 72 hours. The solvent used in the two-dehydration condensation reaction may be methanol, ethanol, CH ₂ Cl ₂ , acetonitrile, DMF, polar aprotic solvent and protonic solvent, and these may be selected according to the type of catalyst. Can be. In particular, in the case of methanol and ethanol, which are polar protic solvents, ammonium acetate catalysts showed good results, and in the case of polar aprotic solvents, a catalyst of triethyl amine / paratoluene sulfonic acid showed a preferable catalyst result.

The compound of formula 1 prepared according to the present invention includes both cis and trans forms which are geometric isomers.

The compound of Chemical Formula 1 prepared according to the present invention may be usefully used in an organic electroluminescent device which emits light of a red region having improved color purity by reducing the half width of the emission wavelength.

In the definition of the substituent used in the compound according to the present invention, the alkyl group having 1 to 20 carbon atoms includes a straight or branched type, and preferably includes a straight or branched type having 1 to about 12 carbon atoms. . More preferred alkyl groups are lower alkyls having 1 to 6 carbon atoms. Examples of such alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, iso-amyl, hexyl and the like. Even more preferred are lower alkyl substituents having from 1 to 3 carbon atoms. One or more hydrogen atoms in such alkyl groups, preferably 1 to 5 hydrogen atoms, may be substituted with other substituents such as halogen atoms, amino groups, alkylamino groups having 1 to 20 carbon atoms, nitro groups, hydroxyl groups, carboxyl groups and cyano groups, It may be substituted with an alkoxy group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a heterocycle group having 4 to 36 carbon atoms, and an aryl group having 6 to 36 carbon atoms.

In the definition of the substituent used in the compound according to the present invention, an aryl group having 6 to 36 carbon atoms is used alone or in combination to mean a carbocyclic aromatic system having 6 to 36 carbon atoms including at least one ring, and the ring Can be attached or fused together in a pendant manner. The term aryl includes aromatic groups such as phenyl, naphthyl, tetrahydronaphthyl, indane and biphenyl. More preferred aryl is phenyl. At least one hydrogen atom in the aryl group, preferably 1 to 5 hydrogen atoms, is substituted with other substituents, such as halogen atoms, amino groups, nitro groups, hydroxyl groups, carboxyl groups cyano groups, and alkylamino groups having 1 to 20 carbon atoms. It may be substituted with an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms.

In the definition of the substituent used in the compound according to the present invention, a heteroalkyl group having 1 to 20 carbon atoms means cyclic, branched or straight chain containing carbon, hydrogen and at least one hetero atom, and the hetero atom Is generally nitrogen, oxygen, silicon, phosphorus or sulfur. When the heteroalkyl group includes a nitrogen atom, the nitrogen atom may be primary, secondary, tertiary or quaternary or exist in various forms such as amide or sulfonamide. The heteroalkyl group may include one or more unsaturated bonds, for example double bonds and triple bonds. They preferably have 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms. In such heteroalkyl groups, one or more hydrogen atoms, preferably 1 to 5 hydrogen atoms, are substituted with other substituents, for example halogen atoms, amino groups, nitro groups, hydroxyl groups, carboxyl groups cyano groups, alkylamino groups having 1 to 20 carbon atoms. It may be substituted with an alkyl group having 1 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, or an alkenyl group having 2 to 20 carbon atoms.

Among the definitions of substituents used in the compounds according to the invention, heterocycle groups include substituted, partially substituted and unsubstituted heteroatom-containing rings, which heteroatoms may be selected from nitrogen, sulfur, silicon, phosphorus and oxygen have. Examples of saturated heterocycles include saturated 3 to 6 membered heteromonocycle groups containing 1 to 4 nitrogen atoms (eg pyrrolidinyl, imidazolidinyl, piperidino, piperazinyl); Saturated 3 to 6 membered heteromonocycle groups (eg morpholinyl) containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms; Saturated 3 to 6-membered heteromonocycle groups (eg thiazolidinyl) containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms are mentioned. Examples of partially saturated heterocyclyls include dihydrothiophene, dihydropyran, dihydrofuran, and dihydrothiazole. Examples of unsaturated heterocycle groups, also called heteroaryl groups, include pyrrolyl, pyrrolinyl, imidazolyl, pyrazolyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, pyrimidyl, pyrazinyl, pyridazinyl Unsaturated 5-6 membered heteromonocycle groups containing 1-4 nitrogen atoms such as triazolyl (e.g. 4h-1,2,4-triazolyl, 1h-1,2,3-triazolyl, 2H- 1,2,3-triazolyl); Unsaturated condensed heterocycle containing 1 to 5 nitrogen atoms, such as indolyl, isoindoleyl, indorylzinyl, benzimidazolyl, quinolyl, isoquinolyl, indazolyl, benzotriazolyl, tetrazopyridazinyl, etc. Groups (eg tetrazolo [1,5-b] pyridazinyl); Unsaturated 3 to 6-membered heteromonocycle groups containing oxygen such as pyranyl, 2-furyl, 3-furyl and the like; Unsaturated 5- to 5-membered heteromonocycle groups containing sulfur atoms such as 2-thienyl and 3-thienyl; Unsaturated 5- to 6-membered heteromonocycle groups containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms such as oxazolyl, isoxazolyl, oxdiazolyl and the like (for example, 1,2,4-oxadiazolyl , 1,3,4-oxadiazolyl, 1,2,5-oxadiazolyl); Unsaturated condensed heterocycle groups containing 1 to 2 oxygen atoms and 1 to 3 nitrogen atoms (eg benzoxazolyl, benzoxadiazolyl); Unsaturated 5- to 6-membered heteromonocycle groups containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms such as thiazolyl and thiadiazolyl (for example, 1,2,4-thiadiazolyl, 1,3,4 -Thiadiazolyl, 1,2,5-thiadiazolyl); And unsaturated condensed heterocycle groups containing 1 to 2 sulfur atoms and 1 to 3 nitrogen atoms (for example, benzothiazolyl and benzothiadiazolyl). The term also includes structures in which the heterocycle is fused with an aryl group. Examples of such fused bicyclic cyclic compounds include benzofuran, benzothiophene and the like. The heterocycle group may have 1 to 3 substituents such as lower alkyl, halogen atom, hydroxy, oxo, amino and lower alkylamino. Preferred heterocycles include 5 to 10 membered fused or unfused structures.

The alkoxy group, which is a substituent used in the compound of the present invention, includes both oxygen-containing linear or branched groups each having an alkyl or aryl moiety having 1 to 20 carbon atoms. Lower alkoxy groups having 1 to 6 carbon atoms are more preferred alkoxy groups. Examples of such functional groups include methoxy, ethoxy, propoxy, butoxy and t-butoxy. Even more preferred are lower alkoxy groups having 1 to 3 carbon atoms.

The alkenyl group, which is a substituent used in the compound of the present invention, refers to an aliphatic hydrocarbon group which may be linear or branched having 2 to 20 carbon atoms containing a carbon-carbon double bond. Preferred alkenyl groups have 2 to 12 carbon atoms in the chain, more preferably 2 to 6 carbon atoms in the chain. Branched means that one or more lower alkyl or lower alkenyl groups are attached to the alkenyl straight chain.

Has a structure of -N (R _a ) (R _b ) which is an amine group which is a substituent used in the compound of the present invention, wherein R _a and R _b are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms And a substituted or unsubstituted aryl group having 4 to 10 carbon atoms.

Specific examples of the compound of the present invention include compounds represented by the following formulas (8) to (23).

The present invention also provides an organic electroluminescent device comprising the compound of Formula 1 as a light emitting material alone or in a mixture of two or more kinds in the light emitting layer constituting the organic layer.

The structure of the organic electroluminescent device according to one embodiment of the present invention is shown in FIG. 1. As shown in FIG. 1, the organic electroluminescent device of the present invention may be configured in a multilayer form in which a substrate 1, a transparent electrode 2, an organic layer 4, and a metal electrode 3 are sequentially stacked.

The operating mechanism of the organic EL device generally includes a series of processes such as injection of holes and electrons from an electrode, generation of an electronic excited state by recombination of holes and electrons, and emission from an excited state. As shown in FIG. 2, the organic layer is disposed between two different electrodes. Herein, the organic layer exhibits excellent characteristics of the stacked type device in which the light emitting layer and the charge transport layer are combined, rather than the single layer type device including the light emitting layer. This is because an appropriate combination of the light emitting material and the charge transport material reduces the energy barrier when charge is injected from the electrode, and the charge transport layer binds the holes or electrons injected from the electrode to the light emitting layer region to balance the number of holes and electrons injected. Because it plays a role to achieve.

Therefore, the organic layer of the present invention is preferably an electron transporting layer / light emitting layer / hole transporting layer, an electron transporting light emitting layer / hole transporting layer, or an electron transporting layer / hole aqueous light emitting layer, as shown in Figs. In this case, the hole transporting material used in the hole transporting layer or the hole transporting light emitting layer may include at least one selected from the group consisting of an arylamine derivative, a phthalocyanine compound, and a triphenylene derivative, and is used in the electron transporting layer or the electron transporting emitting layer. The electron transporting material may include a metal complex compound or a nitrogen-containing aromatic ring compound.

Specifically, the organic electroluminescent element A shown in FIG. 1 has a multilayer form in which a substrate 1, a transparent electrode (anode) 2, an organic layer 4, and a metal electrode (cathode) 3 are sequentially stacked. At this time, the substrate 1 is for forming an element, and may use a conventional material such as glass, plastic, or the like; As the transparent electrode (anode) 2, indium lead oxide (hereinafter abbreviated as ITO), SnO ₂ , or the like can be used; The metal electrode (cathode) 3 may use a conventionally known electrode material, preferably a metal such as Li, Mg, Ca, Ag, Al, In, or an alloy thereof, and may have a single layer or a multilayer structure of two or more layers. Can be. In addition, the organic layer 4 may be composed of a single layer or a multilayer of two or more layers including one or more compounds selected from the compounds of Formula 1 of the present invention as light emitting materials. The compound of formula 1 of the present invention may be included alone or in a mixture of two or more kinds of one or more of the layers constituting the organic layer as a light emitting material, for example, Alq ₃ , rubrene (rubrene) and the like Can be added.

The organic electroluminescent device B shown in FIG. 2 is a multilayer form in which a substrate 1, a transparent electrode (anode) 2, an organic layer 4a, and a metal electrode (cathode) 3 are sequentially stacked, among which an organic layer. 4a is a structure in which the hole transport layer 5 and the electron transporting light emitting layer 6 are stacked. At least one compound of the compound of formula 1 of the present invention is included in the electron transporting light emitting layer 6 as a light emitting material. Here, the substrate 1, the transparent electrode (anode) 2 and the metal electrode (cathode) 1 are as mentioned above. The hole transport layer 5 is a conventional hole transport material such as 4,4-bis [N- (1-naphthyl) -N-phenyl-amine] biphenyl (hereinafter abbreviated as α-NPD), N, N-diphenyl-N, N-bis (3-methylphenyl) -1,1-biphenyl-4,4-diamine (hereinafter abbreviated as TPD), poly- (N-vinylcarbazole) (hereinafter as PVCz) Abbreviated-name) etc. can be used individually or in mixture of 2 or more types, and 2 or more layers in which another layer was laminated may be sufficient. The electron transporting light emitting layer 6 may be used alone or in combination of two or more kinds of the compound of the formula (1) as a light emitting material, or other conventionally known electron transport material, for example Alq ₃ , Rubrene and the like may be added alone or in combination of two or more thereof. In addition, in order to improve device characteristics such as efficiency and lifespan, various hole injection layers or anode buffer layers, such as copper phthalocyanine, are inserted between the anode 2 and the hole transport layer 5 as necessary, or the cathode 3 ) And an electron injection layer or a cathode buffer layer, such as LiF, may be inserted between the electron transport layer 6 and the electron transporting light emitting layer 6.

The organic electroluminescent device C shown in FIG. 3 is a multilayered structure in which a substrate 1, an anode 2, an organic layer 4a and a cathode 3 are sequentially stacked, where the organic layer 4a is a hole transporting light emitting layer ( 7) and the electron transport layer 8 are laminated. At least one compound of the compound of formula 1 of the present invention is included in the hole transporting light emitting layer 7 as a light emitting material. Here, the substrate 1, the transparent electrode (anode) 2 and the metal electrode (cathode) 3 are as mentioned above. The hole transporting light emitting layer 7 may be used alone or in combination of two or more of the compounds of the formula (1) as a light emitting material, or may be added to the compound of the formula (1), for example, other compounds, such as TPD. Further, the electron transport layer 8 is Alq _3, rubrene, etc. may be a conventionally known electron transporting material used alone or in combination of two or more kinds, can be more than two layers of different layers are laminated. In addition, in order to improve device characteristics such as efficiency and lifespan, various hole injection layers or anode buffer layers such as copper phthalocyanine or the like are inserted between the anode 2 and the hole transporting light emitting layer 7 as necessary, or the cathode ( Between the 3) and the electron transport layer 8, various conventional electron injection layers such as LiF, a cathode buffer layer, or the like may be inserted.

The organic electroluminescent device D shown in FIG. 4 is a multi-layered structure in which a substrate 1, a transparent electrode (anode) 2, an organic layer 4b, and a metal electrode (cathode) 3 are sequentially stacked. 4b is a structure in which the hole transport layer 9, the light emitting layer 10, and the electron transport layer 11 are stacked. At least one compound of Formula 1 of the present invention is included in the light emitting layer 10 as a light emitting material. Here, the substrate 1, the transparent electrode (anode) 2 and the metal electrode (cathode) 1 are as mentioned above. The hole transport layer 9 may be used alone or in combination of two or more of conventional hole transport materials, for example, α-NPD, TPD, PVCz, or the like, or may be two or more layers in which other layers are laminated. The light emitting layer 10 may be used alone or in combination of two or more of the compounds of the formula (1) as a light emitting material, or other compounds, such as Alq ₃ , rubrene or the like to the compound of the formula (1) or You may mix and add 2 or more types. The electron transporting layer 11 may be used alone or as a mixture of two or more kinds of conventionally known electron transporting materials such as Alq ₃ and rubrene, and may be two or more layers in which other layers are laminated. In addition, in order to improve device characteristics such as efficiency and lifespan, various hole injection layers or anode buffer layers such as copper phthalocyanine or the like are inserted between the anode 2 and the hole transport layer 9 as necessary, or the cathode 3 Between the electron transport layer 11 and various conventional electron injection layers such as LiF or cathode buffer layer may be inserted.

The above-mentioned organic electroluminescent elements (Figs. 1 to 4) of the present invention are driven by applying a voltage between the anode 2 and the cathode 3, and the voltage is usually using direct current, but pulse or alternating current may also be used. .

As such, the compound of Chemical Formula 1 of the present invention exhibits excellent chemical and electrical stability, heat resistance, durability, luminous efficiency, luminous luminance and color purity, and thus may be usefully used as a red light emitting material of an organic electroluminescent device.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are not intended to limit the invention only.

Preparation Example 1 Preparation of Red Luminescent Material

The luminescent material of Chemical Formula 12 was prepared according to the method according to Scheme 1 below:

<Formula 12>

After dissolving 3 g of 1,4-benzodioxan-6-yl methyl ketone of Formula 1a in 100 mL of ethanol, 1.56 g of maleonitrile is added, and 1.56 g of ammonium acetate is added. After refluxing at 80 ^° C. for 24 hours, the compound of formula 1b can be obtained in 75% yield through chromatographic separation (developing solvent, ethyl acetate: hexane 1: 7). 1.7 g of the compound of Formula 1b was dissolved in 50 ml of acetonitrile solvent, and then 1.0 g of the compound of Formula 1d was added. After dehydration and condensation reaction, 0.1 ml of piperidine was added, and the mixture was refluxed at 80 ^° C. for 12 hours. Chromatographic separation (developing solvent, ethyl acetate: nucleic acid 1:10) gave the compound of Formula 1c in 60% yield.

NMR analysis of the obtained compound 1c: ¹ H-NMR (300 MHz, CDCl ₃ ) 7.89-7.45 (m, 19H) 7.20 (d, 1H) 7.14 (d, 1H), 6.95 (d, 1H) 6.84 (d, 1H )

Preparation Example 2 Preparation of a Red Light Emitting Material of Formula 14

<Formula 14>

After dissolving 19.6 g (0.1 mol) of 4-phenyl acetophenone of Chemical Formula 1a in 200 mL of ethanol, 6.6 g (0.1 mol) of maleonitrile was added and ammonium acetate (0.7 g) was added thereto. After refluxing at 80 ^° C. for 24 hours, the compound of formula 1b was obtained by chromatography separation (developing solvent, ethyl acetate: hexane 1: 7) in 75% yield. 2.4 g of the compound of Formula 2b was dissolved in 50 ml of acetonitrile solvent, and 1.0 g of 2-methoxy-5- (2-isopropyloxy) terephthalaldehyde was added thereto. After dehydration and condensation reaction, 0.1 ml of piperidine was added, and the mixture was refluxed at 80 ^° C. for 12 hours. Chromatographic separation (developing solvent, ethyl acetate: hexane 1:10) gave the compound of formula 2c in 60% yield.

NMR analysis of Compound 2c: ¹ H-NMR (300 MHz, CDCl ₃ ) 7.95-7.42 (m, 20H), 7.18 (d, 1H), 7.13 (d, 1H), 7.04 (d, 1H), 6.92 (d , 1H), 4.56 (tt, 1H), 3.84 (s, 3H), 1.56 (d, 6H)

Preparation Example 3 Preparation of a Red Light Emitting Material of Formula 10

<Formula 10>

After dissolving 3 g of 1,4-benzodioxan-6-yl methyl ketone of Chemical Formula 3a in 100 mL of ethanol, 1.56 g of maleonitrile was added and 1.56 g of ammonium acetate was added. After refluxing at 80 ^° C. for 24 hours, the compound of formula 3b was obtained by chromatography separation (developing solvent, ethyl acetate: hexane 1: 7) in 75% yield. 2.2 g of the compound of formula 3b was dissolved in 50 ml of acetonitrile solvent, and then 1.0 g of 2-methoxy-5- (2-isopropyloxy) terephthalaldehyde was added. After dehydration and condensation reaction, 0.1 ml of piperidine was added, and the mixture was refluxed at 80 ^° C. for 12 hours. Chromatographic separation (developing solvent, ethyl acetate: hexane 1:10) gave the compound of formula 3c in 60% yield.

Results of NMR analysis of the compound of formula 3c: 1H-NMR (300MHz, CDCl3) 7.90-7.00 (m, 8H) 7.19 (d, 1H) 7.13 (d, 1H) 7.01 (d, 1H) 6.92 (d, 1H) 4.55 (tt.1H) 3.80 (s, 3H) 1.53 (d, 6H)

Example 1:

ITO (Indium Tin Oxide) coated glass (Asahi Glass Co., Ltd., sheet resistance 8 Ω / cm ² ) was transparent by ultrasonic cleaning with water-based detergent, ultrapure water, isopropyl alcohol and methanol sequentially. An electrode was produced. Subsequently, using a mixture of poly- (N-vinylcarbazole) represented by the following formula (24) and TPD (triphenyldiamine derivative) represented by the following formula (25) in a molar ratio of 1: 1, the hole transport layer was 40 nm by spin coating. It formed into a film on the said ITO coating glass by thickness. Subsequently, Alq ₃ and the compound prepared in Preparation Example 1 were used as an electron transporting light emitting layer in an equivalent ratio of 30: 1, and co-deposited at a thickness of 50 nm and a speed of 0.1 nm / second to contact the hole transport layer. Then, an MgAg alloy (weight ratio 10: 1) was vacuum-deposited so as to have a film thickness of 600 nm in a circular shape having a diameter of 3 mm as a cathode thereon, thereby producing an organic EL device as shown in FIG.

The electroluminescence (EL) spectrum was measured by PR-650 of Photo Research, by applying a forward bias DC voltage to the organic EL device thus prepared, and is shown in FIG. 6. It can be seen from FIG. 6 that the organic electroluminescent device manufactured according to the present invention has an emission peak showing the maximum emission intensity at 612 nm, and the region corresponds to the red emission region.

In addition, a voltage-luminance graph of the organic electroluminescent device is shown in FIG. 7. 7, it can be seen that the organic electroluminescent device exhibits a maximum brightness of 9500 cd / m ² at a 14V driving voltage.

Example 2

An organic electroluminescent device was manufactured by a method similar to Example 1, except that the compound prepared in Preparation Example 2 was used instead of the compound prepared in Preparation Example 1. The manufactured organic electroluminescent device had an emission peak showing the maximum emission intensity at 594 nm corresponding to the red emission region, and showed a luminance of 9500 cd / m ^{2 at} a 14 V driving voltage.

Example 3

An organic electroluminescent device was manufactured by a method similar to Example 1, except that the compound prepared in Preparation Example 3 was used instead of the compound prepared in Preparation Example 1. The manufactured organic electroluminescent device had a light emission peak showing a maximum emission intensity at 590 nm corresponding to a red light emitting region, and showed a luminance of 9100 cd / m ^{2 at} a 14 V driving voltage.

The light emitting material of Chemical Formula 1 according to the present invention exhibits excellent chemical and electrical stability, heat resistance, durability, luminous efficiency, light emission luminance and color purity, and thus may be usefully used as a red light emitting material of an organic electroluminescent device.

1, 3 and 4 are schematic cross-sectional views of an organic electroluminescent device according to the present invention,

2 is a schematic cross-sectional view of an organic electroluminescent device manufactured in Example 1 according to the present invention,

Figure 5 shows the UV absorption and photoluminescence (PL) spectrum of the compound prepared in Preparation Example 1 according to the present invention,

Figure 6 shows the electroluminescence (EL) spectrum of the organic electroluminescent device manufactured in Example 1 according to the present invention,

7 shows a voltage-luminance graph of the organic electroluminescent device manufactured in Example 1 according to the present invention.

<Description of Signs of Major Parts of Drawings>

1: substrate 2: transparent electrode (anode)

3: metal electrode (cathode) 4 (4a and 4b): organic layer

5: hole transport layer 6: electron transporting light emitting layer

7: hole transporting light emitting layer 8: electron transporting layer

9: hole transport layer 10: light emitting layer

11: electron transport layer A, B, C and D: organic electroluminescent device

Claims (7)

Red light emitting material characterized in that represented by the formula (1): <Formula 1> Wherein R ₁ , R ₂ , R _3, R ₄ , R ₅ , and R ₆ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl having 6 to 36 carbon atoms. Group, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms, In the above formula, D is an aromatic ring of Formula 2 or 3 or two or more aromatic rings. <Formula 2> <Formula 3> R ₇ to R ₁₆ each independently represent a hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 36 carbon atoms, a substituted or unsubstituted hetero atom having 1 to 20 carbon atoms. An alkyl group, a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms, a substituted or unsubstituted amine group having 0 to 20 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms. The red light emitting material of claim 1, wherein the compound of Formula 1 is any one of the compounds of Formulas 8 to 23. <Formula 8> <Formula 9> <Formula 10> <Formula 11> <Formula 12> <Formula 13> <Formula 14> <Formula 15> <Formula 16> <Formula 17> <Formula 18> <Formula 19> <Formula 20> <Formula 21> <Formula 22> <Formula 23> The dehydration condensation reaction of the compound of Formula 6 and the compound of Formula 7 to produce a red light emitting material of the formula (1) according to claim 1 wherein the red light emitting material. <Formula 6> (Wherein R ₁ and R ₂ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 36 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms) Or a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms) <Formula 7> (Wherein R ₂ and R ₃ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 36 carbon atoms, a substituted or unsubstituted heteroalkyl group having 1 to 20 carbon atoms) Or a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms, In the above formula, D is an aromatic ring of Formula 2 or 3 or two or more aromatic rings. <Formula 2> <Formula 3> R ₇ to R ₁₆ each independently represent a hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted aryl group having 6 to 36 carbon atoms, a substituted or unsubstituted hetero atom having 1 to 20 carbon atoms. An alkyl group, a substituted or unsubstituted heterocycle group having 4 to 36 carbon atoms, a substituted or unsubstituted amine group having 0 to 20 carbon atoms, or a substituted or unsubstituted alkoxy group having 1 to 20 carbon atoms.) The method of claim 3, wherein the compound of Chemical Formula 6 is obtained by dehydrating a compound of Chemical Formula 4 and a compound of Chemical Formula 5. <Formula 4> Wherein R ₁ and R ₂ are as defined in claim 3 above. <Formula 5> The method of claim 3, wherein the catalyst of the dehydration condensation reaction is a secondary or tertiary amine. An organic light emitting device in which a substrate, a transparent electrode, an organic layer, and a metal electrode are sequentially stacked, wherein the organic layer comprises a red light emitting material of Chemical Formula 1 according to claim 1. The organic electroluminescent device according to claim 6, wherein the organic layer is an electron transporting layer / light emitting layer / hole transporting layer, an electron transporting light emitting layer / hole transporting layer, or an electron transporting layer / hole transporting light emitting layer.