KR100618946B1 - Red luminescent organic compound and organic light-emitting diode including the same - Google Patents

Abstract

Disclosed are a fumaronitrile-based red organic light emitting compound having high efficiency and high quality of red light and 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 the above formula, R ₁ to R ₄ are each independently substituted or unsubstituted alkyl, aryl or fused ring group having up to 40 carbon atoms, R ₅ to R ₁₂ are each Independently hydrogen, a halogen group, a substituted or unsubstituted alkyl group, an alkoxy group, an aryl group, or an amino group.

Red light emitting compound, fumaronitrile, 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, excellent thermal stability fumaronitrile-based red organic light emitting compound and an organic light emitting diode comprising the same It is about.

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 for 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, materials that emit light in the red region (590 nm) are typically 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran (4- ( Although a DCM compound having a dicy anomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran: DCM) structure has been disclosed, the DCM-based red light-emitting compound mainly substitutes a substituent such as an alkyl group with nitrogen. They have low heat resistance and short lifespan of organic electroluminescent devices using them. Other red light emitting materials are known as organometallic complexes based on europium (Appl. Phys. Lett., 65 (17)). , 2124 (1994)), and the organic electroluminescent device using the same has a problem in that the highest luminance is significantly low. Further, Japanese Patent Laid-Open No. 1999-329731 discloses a high-brightness 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. A red light emitting device (USP 6,338,910, Chem Commun., 2003, 2632-2633) using the bound fumaronitrile compound derivative was developed.

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 to R ₄ are each independently substituted or unsubstituted alkyl, aryl or fused ring group having 40 or less carbon atoms, and R ₅ to R ₁₂ are Each independently is hydrogen, a halogen group, a substituted or unsubstituted alkyl group, an alkoxy group, an aryl group, or an amino group.

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

The red organic light emitting compound according to the present invention is a fumaronitrile-based compound having a hole transport / injection capability as well as emitting light by receiving energy generated by recombination of electron-holes, and has a structure of Formula 1 .

In the above formula, R ₁ to R ₄ are each independently substituted or unsubstituted alkyl, aryl, or fused ring group having up to 40 carbon atoms, wherein R ₁ and R ₂ , R ₃ and R ₄ may be each connected by a chemical bond to form a cyclic compound, the cyclic compound may include a hetero element, the hetero element is oxygen (O), sulfur (S), nitrogen (N ) And the like, and a preferable example is nitrogen (N). R ₅ to R ₁₂ are each independently hydrogen, a halogen group, substituted or unsubstituted C 1 to 60; Preferably it is a C1-C36 alkyl group, an alkoxy group, an aryl group, or an amino group, and can form an aryl ring with an adjacent substituent.

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등을 예시할 수 있다.Preferred examples of the red organic compound according to the present invention,

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Etc. can be illustrated.

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 and charge transfer characteristics by appropriately selecting the substituents The organic compound layer which has physical properties, such as these, 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 fumaronitrile compound, which is a red organic light emitting compound according to the present invention, may be synthesized by various organic synthesis methods, for example, using a palladium catalyst C-N formation reaction.

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, conventional compounds such as chinoline derivatives, in particular tris (8-quinolinorate) aluminum (aluminaquinone, Alq ₃ ), may also be used to form these layers. , 25 and 26 function to increase, confine, and combine the holes and electrons injected into the light emitting layer 14. The light emitting layer 14, the hole injection and transport layers 21 and 22 and the electrons are improved. The thicknesses of the injection and transport layers 25 and 26 are not particularly limited and vary depending on the formation method, but usually have a thickness of about 5 to 500 nm.

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 Synthesis of 4,4'-Diisoindolin-α, β-Dicyanostilbin (4,4'-diisoindoline-α, β-dicyanostilbene)

end. Synthesis of 4,4'-dibromo-α, β-dicyanostilbin (4,4'-dibromo-α, β-dicyanostilbe ne)

As shown in Scheme 1 below, 1.96 g of 4-bromo phenylacetonitrile and 1 equivalent of iodine were dissolved in 50 ml of ether, and the temperature of the reaction solution was lowered to -78 ° C. 2.1 equivalents of sodium methoxide (NaOCH ₃ ) dissolved in methanol was added dropwise and stirred at −78 ° C. for 30 minutes. Thereafter, the temperature was raised to 0 ° C., followed by stirring for 4 hours, and then the reaction mixture was quenched in 3% hydrochloric acid and then filtered to obtain 4,4′-dibromo-α, β-dicyanostilbin ( 4,4'-dibromo-α, β-dicyanostilbene) was synthesized (yield: 90%).

I. Synthesis of 4,4'-Diisoindolin-α, β-Dicyanostilbin (4,4'-diisoindoline-α, β-dic yanostilbene)

As shown in Scheme 2, 1 g (2.58 mmol) of 4,4'-dibromo-α, β-dicyanostilbin (4,4'-dibromo-α, β-dicyanostilbene) obtained in Scheme 1, iso 2.1 equivalents of indolin (isoindoline), 0.017 g (3%) of palladium catalyst (Pd (OAc) ₂ ), 0.062 g (12%) of phosphorus compound (P (t-Bu) ₃ ), sodium t-butoxide -butoxide, NaOt-Bu) 3 equivalents were added to 50 ml of ortho-xylene (o-xylene), refluxed and stirred at 140 ° C. for 6 hours, the solvent was removed under reduced pressure and crystallized with methanol to give 4,4′-diisoyne Doline-α, β-dicyanostilbin (4,4'-diisoindoline-α, β-dicyanostilbene) was synthesized (yield: 60%).

Example 2 Synthesis of 4,4'-Diminostilbin-α, β-Dicyanostilbin (4,4'-diiminostil bene-α, β-dicyanostilbene)

As shown in Scheme 3, 1 g of 4,4'-dibromo-α, β-dicyanostilbin (4,4'-dibromo-α, β-dicyanostilbene) obtained in Scheme 1, and iminostilbin ( iminosti lbene) 2.1 equivalents, palladium catalyst (Pd (OAc) ₂ ) 0.017 g (3%), phosphorus compound (P (t-Bu) ₃ ) 0.062 g (12%), sodium t-butoxide , NaOt-Bu) 3 equivalents in 50 ml of ortho-xylene (o-xylene), refluxed and stirred at 140 ° C. for 6 hours, and the solvent was removed under reduced pressure and crystallized with methanol to give 4,4′-diiminostilbin. -α, β-dicyanostilbin (4,4'-diiminostilbene-α, β-dicyanostilbene) was synthesized (yield: 60%).

Example 3 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, 9,10-di (2-naphthyl) anthracene (9,10-di (2-naphthyl) anthracene) as a host and red as synthesized in Examples 1 and 2 as dopant After mixing the light emitting compound (mixing amount: 5% by weight), it was deposited to a thickness of 300 kPa, and Alq ₃ was deposited to a thickness of 200 kPa as an electron transporting 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. The emission wavelength (EL), the luminous efficiency, and the maximum luminance of the manufactured organic light emitting diodes were measured and shown in Table 1 below.

Used compound Light emission wavelength (EL) Efficiency (cd / A) Maximum luminance (cd / m ² ) Compound of Example 1 620 nm 8 cd / A 20000 cd / m ² at 12V Compound of Example 2 610 nm 6 cd / A 15000 cd / m ² at 12V

As can be seen from Table 1, the EL 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 (6)

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

In Formula 1, R ₁ to R ₄ are each independently substituted or unsubstituted alkyl, aryl or fused ring group having 40 or less carbon atoms, and R ₅ to R ₁₂ are Each independently is hydrogen, a halogen group, a substituted or unsubstituted alkyl group, an alkoxy group, an aryl group, or an amino group. The organic light emitting compound of claim 1, wherein R ₁ and R ₂ , R ₃ and R ₄ are each connected by a chemical bond to form a cyclic compound. The organic light emitting compound of claim 2, wherein the cyclic compound comprises a hetero element, and the hetero element is selected from the group consisting of oxygen (O), sulfur (S), and nitrogen (N). The method of claim 1, wherein the organic light emitting compound

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An organic light emitting compound 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 to R ₄ are each independently substituted or unsubstituted alkyl, aryl or fused ring group having 40 or less carbon atoms, and R ₅ to R ₁₂ are Each independently is hydrogen, a halogen group, a substituted or unsubstituted alkyl group, an alkoxy group, an aryl group, or an amino group. The organic light emitting diode of claim 5, wherein the organic compound layer is selected from the group consisting of a light emitting layer, a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.

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