KR101131886B1 - Blue luminescent compound with high luminous efficiency and display device including the same - Google Patents

Abstract

Disclosed are a light emitting compound having a high efficiency of blue electroluminescent properties and excellent life characteristics, which can be used as a light emitting layer forming material of a display device, and a display device including the same. The blue light emitting compound is represented by the following formula.

Wherein L is an auxiliary ligand, and R ¹ and R ² are each independently hydrogen, a substituted or unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon having from 20 to 20 carbon atoms. Is a cyclic alkyl group or an aryl group, a halogen group, a cyano group, and R ³ and R ⁴ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon atoms having 4 to 20 carbon atoms. 20 is a cyclic alkyl group or an aryl group, a ketone group, a halogen group or a cyano group, and n is 1, 2 or 3.

Iridium complex, blue light emission, organic electroluminescent device, light emitting layer, lifetime characteristics

Description

Blue luminescent compound with high luminous efficiency and display device including the same}

The present invention relates to a blue light emitting compound and a display device including the same, and more particularly, a light emitting compound having high efficiency of blue electroluminescent properties and excellent lifespan characteristics, which can be used as a light emitting layer forming material of a display device, and including the same. It relates to a display element.

Among the display devices, an electroluminescence device (EL device) is a self-luminous display device, which does not require a backlight for emitting light, and is capable of fabricating a film in a thin film and a bendable form, as well as manufacturing a film. Pattern formation and mass production by technology is easy. In addition, since the electroluminescent device is a spontaneous light emitting device, it is excellent in brightness and contrast, a wide viewing angle, and a fast response speed.

In 1987, Eastman Kodak Co., Ltd. developed for the first time an organic light emitting device (organic EL device) using a low molecular aromatic diamine and an aluminum complex as a material for forming a light emitting layer [Appl. Phys. Lett. 51, 913, 1987]. The most important factor for determining the luminous efficiency in the organic light emitting device is the light emitting material. Fluorescent materials are widely used as a light emitting material to date, but the development of the light emitting material is one of the best ways to improve the luminous efficiency up to four times in theory due to the mechanism of electroluminescence.

, Red), Ir(ppy)₃(

, Green), Firpic(

, Blue), Irppz(

, Blue) 등의 재료가 알려져 있으며(Baldo 등, Appl. Phys. lett., Vol 75, No. 1, 4, 1999; WO 00/70,655; WO 02/7,492; 한국공개특허공보 2004-14346호;), 특히, 최근 일본, 구미에서 많은 발광 재료들이 연구되고 있다.To date, the iridium (III) complex is widely known as a light emitting light emitting material, and for each RGB (Red, Green, Blue) color, (acac) Ir (btp) ₂ (

, Red), Ir (ppy) ₃ (

, Green), Firpic (

, Blue), Irppz (

, Blue) and the like (Baldo et al., Appl. Phys. Lett., Vol 75, No. 1, 4, 1999; WO 00 / 70,655; WO 02 / 7,492; Korean Patent Publication No. 2004-14346; In particular, many light emitting materials have recently been studied in Japan and Europe.

In the case of red light emitting materials and green light emitting materials, some excellent iridium complex materials have been reported so far, but in the case of blue light emitting materials (luminescent compounds), Firpic, Irppz, etc. of the above formulas have been reported as possible materials, but the life of the materials Since it is significantly lower than the red and green light emitting materials in terms of the mass production and compatibility can be said to be the initial level. In particular, there is a limit that the possibility of mass production is very thin without the development of a host that can maximize the performance of the blue light emitting compound.

Accordingly, it is an object of the present invention to provide a blue light emitting compound that emits blue light with high efficiency and a display device including the same.

Another object of the present invention is to provide a blue light emitting compound having excellent lifespan characteristics and capable of mass production, and a display device including the same.

In order to achieve the above object, the present invention provides a blue light emitting compound represented by the following formula (1).

[Formula 1]

Wherein L is an auxiliary ligand, and R ¹ and R ² are each independently hydrogen, a substituted or unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon having from 20 to 20 carbon atoms. Is a cyclic alkyl group or an aryl group, a halogen group, a cyano group, and R ³ and R ⁴ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon atoms having 4 to 20 carbon atoms. 20 is a cyclic alkyl group or an aryl group, a ketone group, a halogen group or a cyano group, and n is 1, 2 or 3.

The novel blue light emitting compound, i.e., the electroluminescent iridium complex, according to the present invention is a material having excellent life characteristics of materials and high efficiency blue light emitting characteristics even at low doping concentrations, which can be mass-produced, and greatly improve electroluminescent performance. It is possible to improve and solve the absence of the blue light emitting material which has been an obstacle in adopting the light emitting light emitting material. Therefore, it is particularly useful for the manufacture of organic light emitting diodes (organic electroluminescent devices), field effect transistors, photodiodes, photovoltaic cells, solar cells, organic lasers, lasers It can also be widely used in the manufacture of various semiconductor devices such as diodes.

Hereinafter, the present invention will be described in more detail.

The blue light emitting compound according to the present invention is a blue phosphorescent compound, that is, an iridium compound (complex) having blue electrophosphorescent properties, represented by the following formula (1).

,

,

및

로 이루어진 군에서 선택되는 것(여기서, 상기 R_a 및 R_b는, 각각 독립적으로, 치환 또는 비치환된 탄소수 1 내지 10의 알킬기, 알케닐기 또는 아르알킬기이고, R_c-N 및 R_d-N은, 각각 독립적으로, 치환 또는 비치환된 탄소수 3 내지 10의 질소함유 헤테로고리기이다.)이며, 더욱 바람직하게는,

(acac),

(tmd),

(dbm),

(pic),

(pypy),

(pim) 및

(pbm)로 이루어진 군에서 선택되는 리간드이다.Here, L is an auxiliary ligand, a common ligand capable of forming an iridium complex can be used as the auxiliary ligand, preferably,

,

,

And

Selected from the group consisting of wherein R _a and R _b are each independently a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, alkenyl group or aralkyl group, and R _c -N and R _d -N Are each independently a substituted or unsubstituted nitrogen-containing heterocyclic group having 3 to 10 carbon atoms.), More preferably,

(acac),

(tmd),

(dbm),

(pic),

(pypy),

(pim) and

(pbm) is a ligand selected from the group consisting of.

R ¹ and R ² are each independently hydrogen, a substituted or unsubstituted C 1 to 20, preferably 1 to 10, more preferably 1 to 5 linear or branched alkyl or alkoxy groups, substituted Or an unsubstituted cyclic alkyl or aryl group having 4 to 20 carbon atoms, preferably 4 to 10 carbon atoms, a halogen group or a cyano group, and R ³ and R ⁴ are each independently hydrogen, a substituted or unsubstituted carbon atom; 20, preferably 1 to 10, more preferably 1 to 5 linear or branched alkyl or alkoxy groups, substituted or unsubstituted cyclic alkyl or aryl groups having 4 to 20, preferably 4 to 10 carbon atoms, ketones Group, a halogen group or a cyano group, n is 1, 2 or 3; In addition, examples of the substituent to be substituted may include a halogen group, a linear or branched alkyl group having 1 to 5 carbon atoms, and the like.

Preferred examples of the blue light emitting compound represented by Formula 1 may include a blue light emitting compound represented by Formula 2 below.

Here, L, R ³ , R ⁴ and n are as defined in the formula (1), R ⁵ and R ⁶ is hydrogen, substituted or unsubstituted C 1 to 20, preferably 1 to 10, more preferably Preferably a linear or branched alkyl group or an alkoxy group of 1 to 5, a substituted or unsubstituted cyclic alkyl group or an aryl group, a ketone group, a halogen group or a cyano group of 4 to 20, preferably 4 to 10 carbon atoms.

More preferred examples of the blue light emitting compound represented by Chemical Formula 1 may include a blue light emitting compound represented by the following Chemical Formula 2.

Here, L and n are as defined in the formula (1), R ⁵ and R ⁶ is hydrogen, substituted or unsubstituted C 1 to 20, preferably 1 to 10, more preferably of 1 to 5 Linear or branched alkyl or alkoxy groups, substituted or unsubstituted cyclic alkyl or aryl groups having 4 to 20, preferably 4 to 10, carbon atoms, ketone groups, halogen groups or cyano groups.

Specific examples of the blue light emitting compound represented by Chemical Formulas 2 to 3 may include blue light emitting compounds represented by the following Chemical Formulas 4a to 4g.

Here, L and n are as defined in the formula (1).

In general, since the light emitting compound has a very weak property in terms of lifespan, a tris-chelated complex having n of 3, which is excellent in lifespan characteristics, may be preferably used as the light emitting compound of the present invention. Tris-chelate complexes in the case where one or more of the auxiliary ligands (L) are included (n is 1 or 2) are also possible.

The pyridinyl derivative ligand constituting the blue light emitting compound (electroluminescent compound) according to the present invention can be prepared by a known organic synthesis method, for example, the following schemes 1 and 2 (wherein R ¹ to R ⁴ are , May be prepared by applying the manufacturing method shown in formula 1).

As shown in Scheme 1, the halogenpyridine derivative, which is an easily obtainable starting material, is reacted with 2-isopro by nucleophilic reaction with n-butyllithium (n-BuLi) in a tetrahydrofuran (THF) solvent. By reacting with Foxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2-Isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane) Boreinpyridine derivative compounds can be prepared. In addition, as shown in Scheme 2, compound (I) and the boranepyridine derivative were added to [1,1'-bis (diphenylphosphino) ferrocene] -palladium (II) chloride ([ The pyridinyl derivative ligand can be prepared by reacting 1,1'-bis (diphenylphosphino) ferrocene] -palladium (II) chloride: Pd (dppf) Cl ₂ ) and saturated sodium bicarbonate (NaHCO ₃ ) solution. have.

The production method of the pyridinyl derivative ligand according to the present invention is not limited to the production method shown in the reaction schemes 1 and 2, in addition to the production method of the above reaction schemes 1 and 2, or all other methods of preparation of the route are possible. And, if the person skilled in the art can be easily manufactured using a conventional organic synthesis method, detailed description is omitted.

The light emitting compound (iridium complex) according to the present invention may also be prepared by a known organic synthesis method, for example, the following Scheme 3 (wherein, R ¹ to R ⁴ may be obtained from the pyridinyl derivative ligand, It is as defined in the formula (1), n = 2) can be prepared by applying the manufacturing method shown.

As shown in Scheme 3, when n in Formula 1 is 2, iridium trichloride (IrCl ₃ ) and the prepared pyridinyl derivative ligand are 1: 2 to 3, preferably 1: 2.1 to 2.4, more preferably. Preferably, the mixture is refluxed in a solvent in a molar ratio of 1: 2.2, and then diiridium dimer is separated. The solvent may be an alcohol or an alcohol / water mixed solvent, for example, 2-ethoxyethanol, 2-ethoxyethanol / water mixed solvent may be used. Next, the diiridium dimer and the auxiliary ligand LH (in which hydrogen is bonded to L as defined in Chemical Formula 1) are added to an organic solvent such as 2-ethoxyethanol, mixed and heated to emit blue light as a final product. The compound (electroluminescent iridium complex) is produced. The pyridinyl derivative ligand and the ligand L of the final product can be appropriately determined according to the molar ratio to react according to the composition ratio, AgCF which facilitates the reaction by removing one acidic hydrogen of the auxiliary ligand. _{3 SO 3, Na 2 CO 3} , it is preferable to mix and react together in an organic solvent such as ethoxyethanol a base such as NaOH in 2.

The display device according to the present invention will be described with reference to the accompanying drawings.

1 is a cross-sectional view illustrating a configuration of a display device (organic electroluminescent device) according to an exemplary embodiment of the present invention. As shown in FIG. 1, the organic electroluminescent device has a high work function on the substrate 10. A first electrode 12 having a hole is formed as a hole injection electrode (anode), and a light emitting layer 14 including a blue light emitting compound according to the present invention is formed on the first electrode 12. . The light emitting layer 14 may be made of only the light emitting compound according to the present invention, or may include the light emitting compound according to the present invention as a light emitting dopant. Specifically, the light emitting layer 14, together with the blue light emitting compound according to the present invention, tris (8-hydroxyquinoline) -aluminum (III) (tris (8-hydroxyquinoline) -aluminum (III): Alq3) and the like It may further comprise an organic luminescent compound, conventional fluorescent dyes and / or dopants. When the blue light emitting compound of the present invention is used as a dopant, the host used together is 4,4'-N, N'-dicarbazole-biphenyl (4,4'-N, N'-dicarbazole-biphenyl: CBP). , 1,3-bis (N-carbazolyl) benzene (1,3-bis (N-carbazolyl) benzene: mCP), 4,4'-N, N'-dicarbazole-3.3'-dimethyl-biphenyl ( 4,4'-N, N'-dicarbazole-3.3'-dimethyl-biphenyl: CDBP) and the like, and the doping concentration is 1 to 40% by weight of the total compounds constituting the light emitting layer 14, preferably 1 to 20% by weight, or 2 to 20% by mole, preferably 4 to 10% by mole, based on the total moles of all compounds constituting the light emitting layer 14. If the doping concentration is too low, there is a fear that the luminous efficiency is lowered, if too high, there is no particular advantage, it is unnecessary.

A second electrode 16 having a low work function is formed on the emission layer 14 so as to face the first electrode 12 as an electron injection electrode (cathode). When voltage is applied to the first and second electrodes 12 and 16 of the organic electroluminescent device, holes and electrons generated by the first and second electrodes 12 and 16 are injected into the light emitting layer 14. In the molecular structure of the emission layer 14, electrons and holes are combined to emit light, and the emitted light passes through the first electrode 12 and the substrate 10 made of a transparent material to display an image. The substrate 10 of the organic electroluminescent device is electrically insulative, and in particular, when fabricating a device that emits light toward the first electrode 12, the substrate 10 should be made of a transparent material, preferably made of glass or transparent plastic film. The first electrode 12 may be made of indium tin oxide (ITO), polyaniline, silver (Ag), and the like. The second electrode 16 may include aluminum (Al), magnesium (Mg), It may be made of a metal alloy such as calcium (Ca) or lithium-aluminum (Li-Al), magnesium-silver (Mg-Ag).

FIG. 2 is a cross-sectional view of an organic electroluminescent device according to another embodiment of the present invention. In the organic electroluminescent device shown in FIG. The hole injection layer 20, the hole transport layer 22, the hole blocking layer (hole blocking layer) 24, the electron injection layer 26 and the electron transport layer so as to be easily and accurately injected into the 14. (28) is different from the organic electroluminescent element shown in FIG. The hole injection layer 20 and the hole transport layer 22 serves to facilitate the injection of holes from the hole injection electrode 12, such as a transparent ITO thin film electrode, and to transport the holes stably. The injection layer 20 is a porphyrinic compound such as but not limited to phthalocyanine copper disclosed in U.S. Patent No. 4,356,429, for example, 4,4 ', 4''-tris (N-3-methylphenyl-N -Phenyl-amino) triphenylamine (4,4 ', 4 "-tris (N-3-methylphenyl-N-phenyl-amino) triphenylamine: m-MTDATA) or 4,4', 4" -tris (N , N- (2-naphthyl-phenylamino) triphenylamine (4,4 ', 4 "-tris (N, N- (2-naphthyl) -phenylamino) triphenylamine: 2-TNATA) and the like, The hole transport layer 22 is N, N'-bis (1-naphthyl) -N, N'-diphenyl-1,1'-biphenyl-4,4'-diamine (N, N'- bis- (1-naphthyl) -N, N'-diphenyl-1,1-biphenyl-4,4'-diamine: NPB), triphenyldiamine derivatives, styrylamine derivatives, N, N'-diphenyl-N , N'-bis (α-naphthylphenyl) -1,1'-biphenyl-4,4'-diamine (N, N'-diphenyl-N, N'-bis (α-naphthylphenyl) -1,1'-biphenyl-4 It can be formed using a conventional amine derivative having an aromatic condensed ring, such as 4'-diamine (α-NPD), etc. The electron injection layer 26 and the electron transport layer 28 is an electron injection electrode 16 A function of facilitating the injection of electrons from the electron and a function of stably transporting the electrons, the electron injection layer 26, without limitation, lithium quinolate (Liq), sodium chloride (NaCl), cesium fluoride (CsF), lithium oxide (Li ₂ O), barium oxide (BaO), and the like, and the electron transport layer 28 includes, but is not limited to, quinoline derivatives such as tris (8-hydroxyquinoline). -Aluminum (III) (tris (8-hydroxyquinoline)-aluminum (III): Alq3) and the like. The hole blocking layer 24 blocks holes from passing through the light emitting layer 14, and includes, but is not limited to, bis (2-methyl-8-quinolinato) (p-phenylphenolato) aluminum (III). (Bis (2-methyl-8-quinolinato) (p-phenylphenolato) aluminum (III): BAlq) and the like. The layers 20, 22, 24, 26, and 28 function to increase, confine, and combine holes and electrons injected into the light emitting layer 14, and to improve luminous efficiency. The thickness of the light emitting layer 14 and the layers 20, 22, 24, 26, 28 is not particularly limited, and depending on the formation method, the light emitting layer 14 has a thickness of usually 5 to 500nm, The hole injection layer 20 is typically 5 to 100 nm, the hole transport layer 22 is usually 1 to 50 nm, the hole blocking layer 24 is usually 1 to 40 nm, and the electron injection layer 26 is 0.1 to 10 nm. The electron transport layer 28 may have a thickness of about 1 nm to about 50 nm.

The electrodes and layers may be formed by a vacuum deposition method, a spin coating method, or the like, which is commonly used for fabricating an organic electroluminescent device. The blue light emitting compound of the present invention can be applied not only to the organic electroluminescent device having the structure shown in FIG. 1 or 2 but also to the organic electroluminescent device having various structures and various semiconductor devices exhibiting light emission phenomenon by hole-electron coupling. . Structures of such various organic electroluminescent devices are disclosed, for example, in US Pat. Nos. 4,539,507, 5,151,629, and the like.

Hereinafter, the present invention will be described in more detail with reference to specific examples. The following examples are intended to illustrate the invention, and the invention is not limited by the following examples.

Example 1 Synthesis of Blue Light Emitting Compound

end. Synthesis of Pyridine Derivatives of Formula A-1

As shown in Scheme 4, 5.0 g (29 mmol) of 2-bromo-4-methylpyridine was dissolved in 50 mL of tetrahydrofuran (THF) under nitrogen, and 22 mL of n-butyllithium (1.6 M solution in hexane at -78 ° C). ) Was added and stirred for 30 minutes. 7.2 ml (35 mmol) of 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane was slowly added to the reaction mixture and stirred for 30 minutes, followed by reaction temperature. Was raised to room temperature and stirred for 5 hours. The reaction was stopped, and the product was extracted to prepare 4.5 g (20 mmol, Compound A-1, yield 70%) of the pyridine derivative substituted with borane in solid form.

I. Synthesis of Ligands Represented by Formula C-1

As shown in Scheme 5, 4.5 g (20 mmol) of the pyridine derivative (Compound A-1) prepared in the step "A" and 5.8 g (15 mmol) of the compound represented by the following B-1 were added to tetrahydrofuran (THF). Dissolve in 100 ml, add 0.6 g (0.75 mmol) of Pd (dppf) Cl ₂ ([1,1'-bis (diphenylphosphino) ferrocene] palladium (II) chloride) and 60 ml of saturated sodium bicarbonate (NaHCO ₃ ) solution. It was refluxed for 12 hours. After completion of the reaction, the product was extracted with water and ethyl acetate, and purified by silica gel column chromatography to obtain 4.2g (11mmol, 73% yield) of pure ligand represented by the formula (C-1).

All. Synthesis of Blue Light-Emitting Compound of Formula E-1

As shown in Scheme 6, 4.2 g (11 mmol) of the ligand represented by Formula C-1 prepared in step "I" and 1.3 g (4.4 mmol) of iridium trichloride (IrCl ₃ ) were added to 45 mL of 2-ethoxyethanol. It was dissolved and refluxed under nitrogen for 12 hours. The resulting solid was filtered, washed with water, extracted with methylene chloride and recrystallized with a mixed solution of toluene to obtain 4 g (2 mmol, yield 86%) of the μ-dichloro diiridium intermediate represented by Chemical Formula D-1.

Next, 4 g (2 mmol) of the diiridium intermediate (D-1 compound) was dissolved in 50 mL of 2-ethoxyethanol, followed by 0.8 g (8 mmol) of 2,4-pentanedione for 12 hours at 130 ° C. The reaction was carried out to obtain 2 g (2 mmol, yield less than 50%) of a blue light emitting compound represented by Chemical Formula E-1.

Example 2 Synthesis of Blue Light Emitting Compound

end. Synthesis of Pyridine Derivatives of Formula A-1

Using the same method as in Example 1, 4.5g (20mmol, yield 70%) of the pyridine derivative represented by Chemical Formula A-1 was prepared.

I. Synthesis of Ligands Represented by Formula C-2

As shown in Scheme 7 below, except that 5.4 g (15 mmol) of the compound represented by Formula B-2 was used instead of the compound represented by Formula B-1, in the same manner as in Example 1, 3.4 g (9 mmol, 63% yield) of ligand represented by C-2 was obtained.

All. Synthesis of Blue Light-Emitting Compound of Formula E-2

As shown in Scheme 8, 3g (8 mmol) of ligand represented by Chemical Formula C-2 prepared in step "I" and 1.0 g (3.2 mmol) of iridium trichloride (IrCl ₃ ) were dissolved in 45 mL of 2-ethoxyethanol. Reflux under nitrogen for 12 hours. The resulting solid was filtered, washed with water, extracted with methylene chloride and recrystallized with a mixed solution of toluene to obtain 2.8 g (1.5 mmol, 90% yield) of an intermediate di-dichlorodiiridium represented by the following Chemical Formula D-2. .

Next, 2.8 g (1.5 mmol) of the diiridium intermediate (D-2 compound) was dissolved in 50 mL of 2-ethoxyethanol, and 0.7 g (7 mmol) of 2,4-pentanedione at 130 ° C. The reaction was carried out for 12 hours to obtain 1.5 g (1.5 mmol, yield less than 50%) of a blue light emitting compound represented by Chemical Formula E-2.

Example 3 Synthesis of Blue Light Emitting Compound

end. Synthesis of Pyridine Derivatives of Formula A-1

Using the same method as in Example 1, 4.5g (20mmol, yield 70%) of the pyridine derivative represented by Chemical Formula A-1 was prepared.

I. Synthesis of Ligands Represented by Formula C-3

As shown in Scheme 9, except that 5.4 g (15 mmol) of the compound represented by Formula B-3 was used instead of the compound represented by Formula B-1, in the same manner as in Example 1, 4.5 g (13 mmol, 86%) of the ligand represented by Chemical Formula C-3 was obtained.

All. Synthesis of Blue Light Emitting Compound of Formula E-3

As shown in Scheme 10, 4 g (11 mmol) of the ligand represented by Formula C-3 and 1.3 g (4.4 mmol) of iridium trichloride (IrCl ₃ ) represented by Formula C-3 were added to 45 mL of 2-ethoxyethanol. It was dissolved and refluxed under nitrogen for 12 hours. The resulting solid was filtered, washed with water, extracted with methylene chloride and recrystallized with a mixed solution of toluene to obtain 3.8 g (2.0 mmol, 90% yield) of an intermediate di-dichlorodiiridium represented by the following Chemical Formula D-3. .

Next, 3.8 g (2.0 mmol) of the diiridium intermediate (D-3 compound) was dissolved in 50 mL of 2-ethoxyethanol, and 1.0 g (10 mmol) of 2,4-pentanedione was added at 130 ° C. The reaction was carried out for 12 hours to obtain 1.8 g (1.8 mmol, yield less than 50%) of a blue light emitting compound represented by Chemical Formula E-3.

[Examples 4 to 6] Fabrication and Evaluation of Organic Electroluminescent Device

end. Fabrication of Organic Electroluminescent Device

)를 넣고, 챔버 내의 진공도가 10^-6torr에 도달할 때까지 배기시킨 후, 셀에 전류를 인가하여 2-TNATA를 증발시켜 ITO 기판 상에 60nm 두께의 정공 주입층을 증착하였다. 다음으로, 상기 진공 증착 장비 내의 다른 셀에 NPB(

)를 넣고, 셀에 전류를 인가하여 NPB를 증발시켜 정공 주입층 위에 20nm 두께의 정공 전달층을 증착하였다. 다음으로, 상기 진공 증착 장비 내의 다른 셀에 발광 호스트 재료인 mCP(

)를 넣고, 또 다른 셀에는 실시예별로, 하기 표 1에 따라, 상기 실시예 1 내지 3에서 제조한 발광 화합물을 각각 넣은 후(각각 실시예 4, 5 및 6), 두 물질을 다른 속도로 증발시켜 도핑함으로써, 상기 정공 전달층 위에 30nm 두께의 발광층을 증착하였다. 이때의 도핑 농도는 발광층을 구성하는 전체 화합물의 총 몰수에 대하여, 4 내지 10 mol%가 적당하다. 다음으로, 상기 NPB 증착의 경우와 동일한 방법으로, 상기 발광층 위에 정공 차단층으로서, BAlq(

)를 10nm의 두께로 증착시키고, 이어서 전자 전달층으로서, Alq3(

)을 20nm 두께로 증착하였다. 다음으로, 전자 주입층으로서, Liq(

)를 1 내지 2nm 두께로 증착한 후, 다른 진공 증착 장비를 이용하여 알루미늄(Al) 음극을 150nm의 두께로 증착하여 유기 전기 발광 소자(OLED)를 제작하였다.According to Table 1 below, for each embodiment, an organic electroluminescent device (OLED) was manufactured using the blue light emitting compound prepared in Examples 1 to 3 as a light emitting dopant. First, the transparent electrode ITO thin film (resistance: 15Ω / □) obtained from OLED glass (manufactured by Samsung-Corning) was subjected to ultrasonic cleaning using trichloroethylene, acetone, ethanol and distilled water sequentially, and then stored in isopropanol. It was used after. Next, the ITO substrate is installed in the substrate folder of the vacuum deposition equipment, and 2-TNATA (

), And evacuated until the vacuum in the chamber reached 10 ^-6 torr, and then applied a current to the cell to evaporate 2-TNATA to deposit a 60 nm thick hole injection layer on the ITO substrate. Next, NPB (to another cell in the vacuum deposition equipment)

), A current was applied to the cell, and NPB was evaporated to deposit a 20 nm thick hole transport layer on the hole injection layer. Next, mCP (the light emitting host material) is applied to another cell in the vacuum deposition apparatus.

) Into another cell, and according to Examples, the light emitting compounds prepared in Examples 1 to 3, respectively, according to Table 1 below (Examples 4, 5, and 6, respectively), and the two materials at different speeds. By evaporation and doping, a light emitting layer having a thickness of 30 nm was deposited on the hole transport layer. In this case, the doping concentration is preferably 4 to 10 mol% based on the total number of moles of all the compounds constituting the light emitting layer. Next, in the same manner as in the case of NPB deposition, BAlq (

) Is deposited to a thickness of 10 nm, and then Alq3 (

) Was deposited to a thickness of 20 nm. Next, as the electron injection layer, Liq (

) Was deposited to a thickness of 1 to 2 nm, and then an aluminum (Al) cathode was deposited to a thickness of 150 nm using another vacuum deposition equipment to fabricate an organic electroluminescent device (OLED).

I. Evaluation of Optical Properties of Blue Emitting Compounds

Complexes with high synthetic yields for each material were vacuum sublimed and purified under 10 ⁻⁶ torr to be used as dopants for the OLED light emitting layer. For materials with low synthetic yields, only photoluminescent peaks were confirmed. The photoluminescence peak (wavelength) was prepared using a methylene chloride solution having a concentration of 10 ⁻⁴ M or less, and measured using a spectroscopic absorber (manufactured by Shimadzu). The excitation wavelength was 250 nm in the photoluminescence measurement of all materials. The electroluminescence wavelength was measured using a fluorescence photometer (manufactured by Shimadzu). The luminous efficiency of OLED was measured at 10 mA / cm ² and measured using a color luminance meter (product name: BM-7, manufacturer: Topcon). The measurement results are shown in Table 1 below, and in FIGS. 3 to 6, electroluminescence spectra, current density-voltage characteristics, luminance-voltage characteristics, and luminous efficiency (cd) of the organic electroluminescent device of Example 4 (host: mCP). / A) -current density characteristics are shown.

Light emitting compound Light emission wavelength (nm) Electroluminescence Wavelength (nm) Luminous Efficiency (cd / A) Example 4 Example 1 (E-1) 440 456 3.0 Example 5 Example 2 (E-2) 465 476 1.5 Example 6 Example 3 (E-3) 473 490 2.2

From Table 1, it can be seen that the organic electroluminescent device (OLED) using the blue light emitting compound according to the present invention has luminous efficiency of 1.5 to 3.0 cd / A, which is excellent in luminous efficiency. Moreover, the light emission wavelength is 440-473 nm and the electroluminescence wavelength is 456-490 nm, showing favorable blue light emission.

), CDBP(

) 등을 사용할 수 있으며, 이때의 도핑 농도는 발광층을 구성하는 전체 화합물의 총 몰수에 대하여, 4 내지 10 mol%가 적당하다. 상기 mCP 대신 상기 CBP 및 CDBP를 사용한 유기 전기 발광 소자(OLED)의 경우도, 상기 실시예 4 내지 6의 결과와 유사한 결과를 얻을 수 있다.In Examples 4 to 6, as the light emitting host material, in addition to the mCP, CBP (

), CDBP (

), And the doping concentration may be 4 to 10 mol% based on the total number of moles of the total compound constituting the light emitting layer. In the case of the organic electroluminescent device (OLED) using the CBP and the CDBP instead of the mCP, the results similar to those of Examples 4 to 6 can be obtained.

1 is a cross-sectional view of an organic electroluminescent device according to an embodiment of the present invention.

Figure 2 is a cross-sectional view of the organic electroluminescent device according to another embodiment of the present invention.

3 is an electroluminescence spectrum of an organic electroluminescent device using the blue light emitting compound of Example 1 as a dopant (host: mCP).

4 is a graph showing current density-voltage characteristics of an organic electroluminescent device using the blue light emitting compound of Example 1 as a dopant (host: mCP).

5 is a graph showing luminance-voltage characteristics of an organic electroluminescent device using the blue light emitting compound of Example 1 as a dopant (host: mCP).

6 is a graph showing the luminous efficiency (cd / A)-current density characteristics of an organic electroluminescent device using the blue light emitting compound of Example 1 as a dopant (host: mCP).

Claims (9)

A blue light emitting compound represented by the following formula (1). [Formula 1]

Wherein L is an auxiliary ligand, and R ¹ and R ² are each independently hydrogen, a substituted or unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon having from 20 to 20 carbon atoms. Is a cyclic alkyl group or an aryl group, a halogen group, a cyano group, and R ³ and R ⁴ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon atoms having 4 to 20 carbon atoms. 20 is a cyclic alkyl group or an aryl group, a ketone group, a halogen group or a cyano group, and n is 1, 2 or 3. The method of claim 1, wherein L is

,

,

And

R _a and R _b are each independently a substituted or unsubstituted alkyl group, alkenyl group or aralkyl group having 1 to 10 carbon atoms, R _c -N and R _d -N Are each independently a substituted or unsubstituted nitrogen-containing heterocyclic group having 3 to 10 carbon atoms. The method of claim 2, wherein L is

,

,

,

,

,

And

Blue light emitting compound is selected from the group consisting of. The blue light emitting compound of claim 1, wherein the blue light emitting compound is represented by the following Chemical Formula 2. [Formula 2]

Wherein L, R ³ , R ⁴ and n are as defined in Formula 1, and R ⁵ and R ⁶ are each independently hydrogen, a substituted or unsubstituted alkyl or alkoxy group having 1 to 20 carbon atoms, Or a substituted or unsubstituted cyclic alkyl group or aryl group having 4 to 20 carbon atoms, a ketone group, a halogen group or a cyano group. The blue light emitting compound of claim 1, wherein the blue light emitting compound is represented by the following Chemical Formula 3. (3)

Herein, L and n are as defined in Formula 1, and R ⁵ and R ⁶ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon number. 4-20 cyclic alkyl groups or aryl groups, ketone groups, halogen groups or cyano groups. The blue light emitting compound of claim 4 or 5, wherein the blue light emitting compound is selected from the group represented by the following Chemical Formulas 4a to 4g. [Chemical Formula 4a]

[Formula 4b]

[Formula 4c]

[Formula 4d]

[Formula 4e]

[Formula 4f]

[Formula 4g]

Here, L and n are as defined in the formula (1). The blue light emitting compound according to claim 1, wherein the blue light emitting compound is a phosphorescent compound. A first electrode which is a hole injection electrode; A second electrode which is an electron injection electrode; And A display device comprising a blue light emitting compound having a structure of Formula 1, and including a light emitting layer positioned between the first and second electrodes. [Formula 1]

Wherein L is an auxiliary ligand, and R ¹ and R ² are each independently hydrogen, a substituted or unsubstituted linear or branched alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon having from 20 to 20 carbon atoms. Is a cyclic alkyl group or an aryl group, a halogen group, a cyano group, and R ³ and R ⁴ are each independently hydrogen, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or an alkoxy group, substituted or unsubstituted carbon atoms having 4 to 20 carbon atoms. 20 is a cyclic alkyl group or an aryl group, a ketone group, a halogen group or a cyano group, and n is 1, 2 or 3. The display device of claim 8, wherein the display device further comprises at least one layer from the group consisting of a hole injection layer, a hole transport layer, a hole blocking layer, an electron transport layer, and an electron injection layer.

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