KR100697332B1 - Red luminescent organic compound and organic light-emitting diode including the same - Google Patents

Abstract

A quinoacridinylene-based red light emitting compound that emits red light with high efficiency and high quality and has excellent thermal stability, and an organic light emitting diode including the same. The red organic light emitting compound has a chemical formula, and the organic light emitting diode includes a first electrode having a high work function, a second electrode having a low work function, and the red organic light emitting compound, and the first and second At least one organic compound layer positioned between the electrodes.

In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 20 or less carbon atoms, an aminoalkyl group, an alkylamino group, an arylamino group, an aryl group or a heteroaryl group, and R ₃ and R ₄ are each independently 20 carbon atoms The following alkyl groups, aryl groups or heteroaryl groups.

Red, light emitting compound, quinoacrydinylidene, organic light emitting diode, heat resistance, stability

Description

Red luminescent organic compound and organic light-emitting diode including the same}             

1 is a cross-sectional view of an organic light emitting diode according to an embodiment of the present invention.

2 is a cross-sectional view of an organic light emitting diode according to another embodiment of the present invention.

The present invention relates to a red organic light emitting compound and an organic light emitting diode including the same, and more particularly, to a high-efficiency and high-quality red light emitting light, and excellent in thermal stability, quinacridinylene-based red organic light emitting compound and organic light containing the same. It relates to a light emitting diode.

Organic Light-Emitting Diodes (OLEDs), also commonly called EL (Electroluminescence Devices), are liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (Field Emissions). As one of the representative flat panel display devices with Display: FED, etc., it does not need a backlight for light emission, it is possible to manufacture a device in a thin film and bendable form, and it is easy to form patterns and mass production by film manufacturing technology. There is this. In addition, since EL is a spontaneous light emitting device, it has the advantage of excellent luminance and viewing angle characteristics, fast response speed, low driving voltage, and theoretically light emission of all colors in the visible region.

As the material capable of forming the organic light emitting layer of the organic light emitting diode, conductive, non-conductive or semiconducting organic monomolecules, oligomers, or polymers may be used. Conjugated organic host materials with conjugated rings and conjugated organic activators are known. Typical examples of the organic host material include naphthalene, anthracene, phenanthrene, pyrene, benzopyrene, chrisene, picene, carbazole (carbazole), fluorene, biphenyl, terphenyl, qurterphenyl, triphenylene oxide, dihalobiphenyl, transstilbene ), 1,4-diphenyl butadiene, and the like, anthracene, tetracene, pentacene, and the like are known. However, the light emitting layer formed using such a typical light emitting organic single molecule has a disadvantage that the thickness of the light emitting layer is 1 μm or more, and the light emitting layer has a high resistance and a high driving voltage. Therefore, various types of organic monomolecules are being developed that can reduce the thickness of the light emitting layer and lower the resistance and driving voltage of the light emitting layer. Also, a guest material is mixed with a host material having sufficient electrons, hole mobility and luminescence and a dopant exhibiting various color tones. By forming a guest-host doping system, a color light emitting layer having improved luminous efficiency and durability has also been developed.

As such an organic light emitting compound, a material that emits light in the green region (550 nm) may include alumina quinone (Alq3: aluminum-tris (8-hydroxyquinolinate), US Pat. Nos. 4,539,507 and 5,150,006), BeBq2 (10-benzo [ h] quinolinol- beryllium complex.See Chemistry Letters (1993), 905-906), Almq (tris (4-methyl-8-quinolinolate) aluminum), Zn (BTZ) ₂ , Zn (NBTZ) ₂ , An (Oc- BTAZ) ₂ (Jpn, J. Appl. Phys. Vol. 35 (1996), 1339-1341), and the like, and materials emitting light in the blue region (460 nm) are ZnPBOX (Chemistry Letters (1994), 1741-). 1742), organometallic complex compounds such as Balq (Bis (2-methyl-8-quinolinolato) (para-phenyl-phenolato) aluminum), DPVBi (1,4-bis (2), which is a styrylarylene derivative , 2-diphenyl-vinyl) biphenyl) and BczVBi (4,4'-Bis ((2-carbazole) vinylene) biphenyl) are known.

In addition, a material that emits light in the red region (590 nm) is typically 4- (dicyano methylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran (4- (dicyanomethylene) -2 -methyl-6- (p-dimethylaminostyryl) -4H-pyran: DCM) is used, and other US Patent Nos. 3,852,683, 3,986,140, 4,012,376, 4,146,707, 4,769,29, 5,018,160, 5,294,869, 5,409,783, 5,492,942, 5,908,581, 5,935,720, CH Chen and CW Tang, "Design and Synthesis of Red Dopants for Electroluminescence" (Chemistry of Functional Dyes, Vol. 2, pp.536- 543 (1993)), CW Tang, SA Van Slyke, and CH Chen, "Electroluminescence of Doped Organic Thin Films" (Journal of Applied Physics, Vol. 65, pp. 3610-3616 (1989)), Junsheng YU, Zhijian CHEN, Seizo MIYATA, "Red-light-emitting organic electroluminescent devices with bisanil dye as emitter" (Jpn. J. Appl. Phys. Vol. 40 (2001) pp. 3201-3205), etc. There is a color light-emitting compound is disclosed. The conventional DCM-based red light-emitting compound is mainly substituted with a substituent such as an alkyl group to nitrogen, they have a low heat resistance has a disadvantage of short life of the organic electroluminescent device using them.

Other materials emitting light in the red region are known as organometallic complexes based on europium (Appl. Phys. Lett., 65 (17), 2124 (1994)). 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, but has a disadvantage in that the molecular color purity does not reach a reference value. Recently, phosphorescent materials using a second dopant such as rubrene or an iridium metal compound have been studied (see US Patent Publications 2002 / 0121638A1 and 2002/0034656 A1). There is room for improvement due to insufficient film stability.

Accordingly, an object of the present invention is to provide a red organic light emitting compound having excellent thermal stability and an organic light emitting diode including the same.

Another object of the present invention is to provide a red organic light emitting compound which not only facilitates the emission color control but also emits high efficiency and high quality red, and an organic light emitting diode including the same.

In order to achieve the above object, the present invention provides a novel red organic light emitting compound of the formula (1). In addition, the present invention includes a first electrode having a high work function, a second electrode having a low work function, and the red organic light emitting compound, wherein at least one organic compound layer is disposed between the first and second electrodes. It provides an organic light emitting diode comprising. Here, the organic compound layer may be a light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, or an electron transport layer, the organic compound may be used as a host or dopant material of the light emitting layer.

[Formula 1]

In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 20 or less carbon atoms, an aminoalkyl group, an alkylamino group, an arylamino group, an aryl group or a heteroaryl group, and R ₃ and R ₄ are each independently 20 carbon atoms The following alkyl groups, aryl groups or heteroaryl groups.

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

The red organic light emitting compound according to the present invention is a quinoacridinylene-based compound, for example, 5,12-dimethyl-7,14-dimethylene- that emits light by receiving energy generated by electron-hole recombination. 5,7,12,14-tetrahydro-quino [2,3-b] acridine (5,12-dimethyl-7,14-dimethylene-5,7,12,14-tetrahydro-quino [2,3 -b] acridine) has the structure of Formula 1 below.

,

등을 예시할 수 있고, 상기 헤테로아릴기의 바람직한 예로는

, 상기 아릴아미노기의 바람직한 예로는

를 예시할 수 있다. 상기 구조식에서 R₅는 수소기, 할로겐기, 시아노기, 탄소수 20개 이하의 알킬기, 알콕시기, 아미노알킬기, 아미노아릴기 또는 아릴기이고 R은 탄소수 20개 이하의 알킬기, 알콕시기 이다. 상기 화학식 1에서, R₃ 및 R₄는 각각 독립적으로 탄소수 20개 이하의 알킬기, 아릴기 또는 헤테로아릴기이다. In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 20 or less carbon atoms, an aminoalkyl group, an alkylamino group, an arylamino group, an aryl group or a heteroaryl group, and preferred examples of the aryl group include

,

And the like, and preferred examples of the heteroaryl group include

Preferred examples of the arylamino group

Can be illustrated. In the above formula, R ₅ is a hydrogen group, a halogen group, a cyano group, an alkyl group having 20 or less carbon atoms, an alkoxy group, an aminoalkyl group, an aminoaryl group or an aryl group, and R is an alkyl group or alkoxy group having 20 or less carbon atoms. In Formula 1, R ₃ and R ₄ are each independently an alkyl group having 20 or less carbon atoms, an aryl group or a heteroaryl group.

In the red organic light emitting compound according to the present invention, since the emission wavelength and charge / hole injection / transport characteristics change according to the substituents substituted in the basic skeleton of the compound of Formula 1, the desired emission wavelength, charge transfer characteristics, and the like are appropriately selected. The organic compound layer which has the physical property of can be formed. In particular, the red organic light emitting compound according to the present invention has excellent heat resistance and not only improves the lifespan and productivity of the light emitting device, but also emits high efficiency and high quality red light. The quinoacridinylene compound, which is a red organic light emitting compound according to the present invention, can be synthesized by various organic synthesis methods. For example, as shown in Scheme 1, quinacridone used as a green organic light emitting compound (Quinacridone) ) Can be synthesized. Although quinacridone derivatives have excellent fluorescence efficiency, they are known to have short lifespan due to poor thermal stability during device manufacturing.

In Scheme 1, X is a halogen group element such as F, Cl, Br.

1 illustrates a cross-sectional view of an organic light emitting diode according to an embodiment of the present invention. As shown in FIG. 1, an organic light emitting diode according to an embodiment of the present invention has a high work function on a substrate 10. A first electrode 12 having a hole is formed as a hole injection electrode (anode), the light emitting layer 14 containing a red light emitting compound according to the present invention is formed on the first electrode 12 have. In addition, the light emitting layer 14 may include a conventional organic light emitting compound, a conventional fluorescent dye, and / or a dopant together with the red light emitting compound according to the present invention. When the compound of the present invention is used as a dopant with a conventional host material such as 9,10-di (2-naphthyl) anthracene (9,10-di (2-naphthyl) anthracene: ADN), the dopant The content of is preferably 1 to 20% by weight, more preferably 5 to 10% by weight relative to the entire host / dopant mixture. 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 light emitting diode, holes and electrons generated in the first and second electrodes 12 and 16 are injected into the light emitting layer 14, and the light emitting layer In the molecular structure of (14), electrons and holes combine to emit red 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 light emitting diode is electrically insulative, and in particular, when fabricating a device emitting light toward the first electrode 12, the substrate 10 is 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, and the second electrode 16 may be made of Al, Mg, Ca, or LiAl, Mg-Ag. It may be made of a metal alloy such as.

FIG. 2 is a cross-sectional view of an organic light emitting diode according to another embodiment of the present invention. In the organic light emitting diode illustrated in FIG. 2, holes and electrons generated in the first and second electrodes 12 and 16 are respectively formed in the light emitting layer 14. The hole injection and transport layers 21 and 22 and the electron injection and transport layers 25 and 26 are further formed so that they can be easily injected into the? The hole injection and transport layers 21 and 22 have a function of facilitating the injection of holes from the hole injection electrode 12 and a function of stably transporting the holes, and the hole injection layer 21 is not limited to the US. Porphyrinic compounds such as phthalocyanine copper disclosed in patent 4,356,429, for example m-MTDATA (4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenylamine), The hole transport layer 22 is NPB (N, N'-diphenyl-N, N'-bis (1-naphthyl) -1,1'-biphenyl) -4,4'-diamine), triphenyldiamine Derivatives, styrylamine derivatives, α-NPD (N, N'-diphenyl-N, N'-bis (α-naphthyl)-[1,1'-biphenyl] 4,4'-diamine) It can be formed using a conventional amine derivative having an aromatic condensed ring The electron injection and transport layer (25, 26) functions to facilitate the injection of electrons from the electron injection electrode 16 and to stabilize the electrons As a function of transporting, the red light emitting organic compound according to the present invention alone or in combination with conventional compounds such as, but not limited to, chinoline derivatives, in particular tris (8-kinolinorate) aluminum (aluminaquinone, Alq3) It may be used to form the electron transport layer 26. These layers 21, 22, 25, and 26 function to increase, confine and bond the holes and electrons injected into the light emitting layer 14, and improve the luminous efficiency. The thicknesses of the light emitting layer 14, the hole injection and transport layers 21 and 22, and the electron injection and transport layers 25 and 26 are not particularly limited, and depending on the formation method, they are usually about 5 to 500 nm thick. Has

The organic light emitting compound according to the present invention may be used as a host or dopant material of the light emitting layer 14, and according to the potential difference with other layers, the hole injection and transport layers 21 and 22 and / or the electron injection and transport layer ( 25, 26), it may also function to inject / transport electrons and holes. The organic layers may be formed by a vacuum deposition method, such as a vacuum deposition method or a spin coating method commonly used in the manufacture of an organic electroluminescent device. The organic light emitting compound of the present invention can be applied not only to the organic light emitting diode having the structure shown in FIG. 1 or 2, but also to organic light emitting diodes having various structures and various semiconductor devices exhibiting light emitting phenomenon by hole-electron coupling. Such structures of various organic light emitting diodes are disclosed in, for example, US Pat. Nos. 4,539,507, 5,151,629, 6,214,481, 6,387,544, and the like.

Next, preferred examples are provided to help understanding of the present invention. However, the following examples are intended to illustrate the invention, not to limit the invention.

Example 1

end. (4-Bromo-phenyl)-{14- [4-bromo-phenyl) -cyano-methylene] -5,12-dimethyl-5, 14-dihydro-12H-quino [2,3-b] Acridine-7-ylidene} -acetonitrile ((4-Bromo-phenyl)-{14-[(4-bromo-phenyl) -cyano-methylene] -5,12-dimethyl-5,14-dihydro- 12H-quino [2,3-b] acridin-7-ylidene} -acetonitrile)

As shown in Scheme 2, 3.5 g (10 mmole) of quinacridone derivative was dissolved in 30 mL of tetrahydrofuran (THF), and then (4-bromo-phenyl) -acetonitrile ((4-Bromo-phenyl) -acetonitrile) 5.8g (30mmole) was added, 1.2g sodium hydride (NaH) was added, and the mixture was refluxed for 12 hours.

After the reaction was completed, the reaction solution was cooled and water was added to obtain a precipitate. The obtained precipitate was filtered and the title compound was obtained in 20% yield using column chromatography (solvent, methylene chloride (MC): hexane (Hx) = 1: 5).

I. Synthesis of Luminescent Material

As shown in Scheme 3 below, (4-bromo-phenyl)-{14- [4-bromo-phenyl) -cyano-methylene] -5,12-dimethyl-5,14-dihydro-12H -0.4 g of amine was introduced by reacting 0.6 g (1 mmol) of quino [2,3-b] acridin-7-ylidene} -acetonitrile with 0.51 g (3 mmol) of diphenylamine. A light emitting material was obtained (yield 50%).

Example 2 Fabrication of Organic Light Emitting Diode

The glass substrate coated with indium tin oxide (ITO) was ultrasonically cleaned, and again washed with deionized water, then degreased with toluene gas and dried. Next, m-MTDATA was deposited on the ITO electrode to form a hole injection layer by vacuum deposition at a thickness of 300 kW, and α-NPD was vacuum deposited on the hole injection layer to a thickness of 300 kW to form a hole transport layer. On top of the hole transport layer, a red luminescent compound synthesized in Example 1 as 9,10-di (2-naphthyl) anthracene (9,10-di (2-naphthyl) anthracene) and dopant as a host After mixing (mixing amount: 5% by weight), was deposited to a thickness of 300 kPa, Alq3 was deposited to a thickness of 200 kPa as an electron transport layer on top of the organic light emitting layer thus formed.

In addition, an electron injection layer was formed by vacuum depositing LiF to a thickness of 10 에 on the electron transport layer, and an organic light emitting diode was manufactured by forming Al on the electron injection layer by 1200 전자 thick. Photoluminescence (PL), luminous efficiency and maximum luminance of the prepared organic light emitting diode were measured and shown in Table 1 below.

PL Efficiency (cd / A) Maximum luminance (cd / m ² ) 640 nm 6cd / A 35000cd / m ² at 12V

As can be seen from Table 1, the PL spectrum of the organic light emitting diode according to the present invention was shown to emit high-quality red light, it can be seen that the efficiency and maximum brightness of the organic light emitting diode manufactured are both excellent.

As described above, the red organic light emitting compound according to the present invention not only has excellent thermal stability and luminous efficiency, but also has an advantage of showing high quality and various wavelengths of red light depending on substituents. The red light emitting organic compound according to the present invention is particularly useful for the production of full color organic light emitting diodes, field effect transistors, photodiodes, photovoltaic cells, solar cells, organic lasers. It can be widely applied to various semiconductor devices such as an organic laser and a laser diode.

Claims (4)

Red organic light emitting compound having a structure of Formula 1. [Formula 1]

In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 20 or less carbon atoms, an aminoalkyl group, an alkylamino group, an arylamino group, an aryl group or a heteroaryl group, and R ₃ and R ₄ are each independently 20 carbon atoms The following alkyl groups, aryl groups or heteroaryl groups. The method of claim 1, wherein R ₁ and R ₂ are each independently

,

,

And

(Wherein R ₅ is a hydrogen group, a halogen group, a cyano group, an alkyl group having 20 or less carbon atoms, an alkoxy group, an aminoalkyl group, an aminoaryl group or an aryl group, and R is an alkyl or alkoxy group having 20 or less carbon atoms). Red organic light emitting compound is selected from the group consisting of. A first electrode having a high work function; A second electrode having a low work function; And An organic light emitting diode comprising an organic compound of Formula 1 and comprising at least one organic compound layer positioned between the first and second electrodes. [Formula 1]

In Formula 1, R ₁ and R ₂ are each independently an alkyl group having 20 or less carbon atoms, an aminoalkyl group, an alkylamino group, an arylamino group, an aryl group or a heteroaryl group, and R ₃ and R ₄ are each independently 20 carbon atoms The following alkyl groups, aryl groups or heteroaryl groups. The organic light emitting diode of claim 3, wherein the organic compound layer is a light emitting layer, and the organic compound is a host or dopant material of the light emitting layer.

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