KR100770414B1 - Blue luminescent organic compound and organic light-emitting diode including the same - Google Patents

Abstract

Disclosed are a blue light emitting compound having high quality blue light with high efficiency, excellent heat resistance and film forming process, and an organic light emitting diode including the same. The blue light emitting organic compound has the following 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 blue light emitting organic compound, and the first and second It further comprises at least one organic compound layer located between the electrodes.

[Formula]

In the above formula,-(K ₁ ) _n- , R _{1 To} R ₁₀ are as defined in the specification.

Blue, light emitting compound, anthracene, organic light emitting diode, heat resistance, stability.

Description

Blue 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 novel blue light emitting organic compound and an organic light emitting diode including the same, and more particularly, a blue light emitting organic compound having high quality blue light with high efficiency, excellent heat resistance and film forming process, and an organic light emitting diode including the same. (Organic Light-Emitting Diode: OLED).

Organic light emitting diodes, also commonly referred to as EL (Electroluminescence device), are representative flat panel displays with Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Field Emission Display (FED), etc. As one of the devices, there is no need for a backlight for light emission, a device can be manufactured in a thin film and a bendable form, and there is an advantage of easy pattern formation and mass production by a film fabrication technique. 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.

The organic light emitting diode forms an organic light emitting layer having a light emitting property between a transparent electrode such as ITO having a large work function and a metal electrode such as Mg having a small work function, and applies a voltage to the electrode to generate holes and electrons at each electrode. When the organic light emitting layer is bonded to the organic light emitting layer, the organic light emitting layer generates light. Various organic compounds for forming an organic light emitting layer of such an organic light emitting diode are known, for example, US Pat. No. 6,455,720 discloses 2,2- (diarlyl) vinylphosphine. Korean Patent Laid-Open Publication No. 2002-0070333 discloses a blue light emitting compound in which a central portion has a diphenylanthracene structure and an aryl group is substituted at the terminal. See also J. Am. Chem. Soc. 2000. 122, pp. 5695-5109 (Shujun Wang, Warren J. Oldham Jr., Raymond A. Hudack, Jr., and Guillermo C. Bazan) describe the synthesis, properties, and optical properties of materials with tetrahedral oligo (phenylenevinylene) structures. It is disclosed. In addition, U.S. Patent Nos. 5,130,603, 5,811,834, 6,251,531, 6,696,177 and Korean Patent Publication No. 1997-0015712 disclose light emitting devices using an anthracene-based derivatives, and Kodak is an anthracene-based compound used as a host. Phosphorous 9,10-di (2-naphthyl) anthracene (9,10-Di (2-naphthyl) anthracene (ADN)) and derivatives were disclosed, and Toyo Ink Co., Ltd. announced an anthracene-based compound including diarylamine. . However, such conventional anthracene derivatives do not have excellent film forming processability, such as difficulty in forming a uniform thin film, do not have excellent heat resistance, and due to the plate-like structure, aggregation between molecules occurs during deposition, resulting in high efficiency and high quality. There is a problem that can not emit blue light.

Accordingly, an object of the present invention is to provide a blue light emitting organic compound having excellent heat resistance and film forming process and an organic light emitting diode including the same.

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

In order to achieve the above object, the present invention provides a novel blue light emitting organic compound represented by the following formula (1). The present invention also includes at least one organic compound layer comprising a first electrode having a high work function, a second electrode having a low work function, and the blue light emitting organic compound, and positioned between the first and second electrodes. It provides an organic light emitting diode comprising a. 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.

[Formula 1]

In Formula 1,-(K ₁ ) _n -is a single bond direct linking group,-(alkylene) n-, -O- or -S- is a linking group, n is 1 or 2, R ₁ to R ₈ is Each independently is hydrogen, halogen, cyano, substituted or unsubstituted amino, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol or substituted or unsubstituted alkoxy, R ₉ and Each R ₁₀ is independently hydrogen, halogen, cyano, substituted or unsubstituted amino, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol, or substituted or unsubstituted alkoxy.

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

The blue light emitting organic compound according to the present invention is an anthracene-based compound which emits light by receiving energy generated by recombination of electron-holes, and has a structure represented by the following Chemical Formula 1.

In Formula 1,-(K ₁ ) _n -is a single bond direct linking group,-(alkylene) n-, -O- or -S- is a linking group, n is 1 or 2,-(K ₁ ) _n -May be methylene or ethylene. R ₁ to R ₈ are each independently hydrogen, halogen, cyano, substituted or unsubstituted amino, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol, substituted or unsubstituted As alkoxy, for example, the amino group may be alkyl, an arylamino group, and the alkyl may be alkyl having 1 to 20 carbon atoms. Aryl may be aryl having 6 to 32 carbon atoms. R ₉ and R ₁₀ are each independently hydrogen, halogen, cyano, substituted or unsubstituted amino, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol, substituted or unsubstituted As alkoxy, for example, the alkyl may be substituted or unsubstituted alkyl having 1 to 20 carbon atoms, and the aryl is pyrazoline such as amino aryl, heteroaryl, pyrazolinyl, pyrazolidinyl, or the like. It may be a pyrazoline group. The R ₁ to R ₁₀ may be bonded to adjacent skeleton carbons to form a ring, or may be bonded to adjacent groups to form a ring. Such a bond may be bonded to a linking group such as an alkylene group or a direct bond without a linking group. May be The formed ring may be a monocyclic ring or may be a fused ring to form new aryl.

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등을 예시할 수 있다.Non-limiting examples of the blue light emitting organic compound represented by Formula 1 according to the present invention are

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Etc. can be illustrated.

In the blue light emitting organic compound according to the present invention, since the emission wavelength and charge / hole injection / transport characteristics change depending on the substituents or the substituents substituted in the basic skeleton of the compound represented by Formula 1, by appropriately selecting a substituent or the connector An organic compound layer having physical properties such as desired emission wavelength and charge transfer characteristics can be formed. In particular, the blue light emitting organic compound according to the present invention is excellent in heat resistance and not only improves the lifetime and productivity of the light emitting device, but also emits blue light with high efficiency and high quality, and is also useful as a hole and electron transport material. The naphthacene-based compound of Formula 1 according to the present invention is an organic synthesis method of various known anthracene-based compounds as disclosed in the 5,130,603, 5,811,834, 6,251,531, 6,696,177, Republic of Korea Patent Publication No. 1997-0015712 It can be prepared using, and preferably by the Ullmann method or the palladium catalyst CN formation reaction method.

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, the organic light emitting diode includes a first electrode 12 having a high work function on the substrate 10. It is formed as a hole injection electrode (anode), and a light emitting layer 14 containing a blue light emitting compound according to the present invention is formed on the first electrode 12. 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 blue 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 based on 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 blue 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) has a function to facilitate the injection of electrons from the electron injection electrode 16 and to stabilize the electrons. As a function of transporting, but not limited to, a quinoline derivative, in particular, a conventional compound such as tris (8-quinolinorate) aluminum (aluminaquinone, Alq3) may be used to form the electron transporting layer 26. These layers 21, 22, 25, and 26 function to augment, confine, and combine holes and electrons injected into the light emitting layer 14. The light emitting layer 14, hole injection and transport layer ( The thicknesses of the 21 and 22 and the electron injection and transport layers 25 and 26 are not particularly limited, and depending on the formation method, they generally 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 electroluminescent devices and various semiconductor devices having various structures that exhibit light emission by hole-electron coupling. The structure of such various organic light emitting diodes is disclosed, for example, in US Pat. Nos. 4,539,507, 5,151,629, 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 Blue Light Emitting Organic Compound

Synthesis of 10-benzylidene-anthracene-9-one

 As shown in Scheme 1, 1.42 g (7.31 mmol) of anthrone and 0.78 g (7.31 mmol) of benzyl aldehyde were placed in a reactor, and 20 mL of pyridine was added to dissolve the reactant. 0.724 mL (7.31 mmol) of piperidine was added thereto, and the reaction was performed while refluxing for 9 hours. After the reaction was completed, the reaction was cooled, pyridine removed, and the reaction was recrystallized from methanol (MeOH) to synthesize 1.86 g of 10-benzylidene-anthracene-9-one (yield: 90%).

Synthesis of 9-benzylidene-10-methylene-anthracene (9-Benzylidene-10-methylene-anthracene)

As shown in Scheme 2, 2.24 mL (6.72 mmol) of methyl magnesium bromide (MeMgBr) was placed in a reactor, and dissolved by adding 10 mL of tetrahydrofuran (THF), and then synthesized 10-benzylidene-anthracene. 0.95 g (3.4 mmol) of -9-one was droppedwise at 40 ° C and the reaction was carried out with stirring for 15 hours. After the reaction was completed, 15 mL of 10% by weight of ammonium chloride (NH ₄ Cl) was added to the reaction, the organic layer was separated, dried, and the dried reactant was placed in 10 mL of toluene, and then p-toluenesulphonic After adding 0.005 g of acid monohydrate (p-toluenesulfonic acid monohydrate), the reaction was performed while stirring at 110 ° C. for 3 hours. After the reaction was completed, the reaction was cooled, washed with ₂ % by weight sodium carbonate (Na ₂ CO ₃ ), and the organic layer was separated and dried to obtain 0.48 g of 9-benzylidene-10-methylene-anthracene. Synthesis (yield: 50%).

Synthesis of 9-benzylidene-10-bromomethylene-anthracene (9-Benzylidene-10-bromomethylene-anthracene)

As shown in Scheme 3 below, 1.4 g (5 mmol) of the synthesized 9-benzylidene-10-methylene-anthracene was added to a reactor, 30 mL of carbon tetrachloride (tetrachloro methane, CCl ₄ ) was added thereto, and then dissolved in bromine. (Br ₂ ) The mixed solution of 0.8 g (5 mmol) dissolved in 10 mL of carbon tetrachloride was dropped dropwise at 0 ° C., and the reaction was performed at 0 ° C. for 7 hours with stirring. After the reaction was completed, the solvent in the reaction was concentrated, the concentrated reaction was dissolved in 50 mL of toluene, and then 5.6 g of pyridine was added and the reaction was stirred at 110 ° C. for 3 hours. Was performed. After the reaction was completed, the reaction was cooled, the reaction was neutralized by addition of 5% by weight hydrochloric acid (HCl), the organic layer was separated, and concentrated to give 9-benzylidene-10-bromomethylene-anthracene 0.72 g was synthesized (yield: 40%).

Synthesis of Blue Luminescent Organic Compounds

As shown in Scheme 4 below, 0.5 g (2.1 mmol) of Mg and 5 mL of tetrahydrofuran were added to a reactor under nitrogen (N ₂ ) gas condition, and the synthesized 9-benzylidene-10-bromomethylene -The liquid which dissolved 0.72 g (2 mmol) of anthracene in 15 mL of tetrahydrofuran was dropped dropwise, and then the reaction was stirred until Mg was dissolved at room temperature, and the synthesized 9-benzylidene was again added to the stirred reaction. A liquid in which 0.72 g (2 mmol) of 10-bromomethylene-anthracene was dissolved in 15 mL of tetrahydrofuran was added dropwise, followed by reaction at 70 ° C. for 15 hours. After the reaction was completed, the reaction mixture was cooled down, 10 wt% hydrochloric acid (HCl) was added to adjust the pH of the reactant to 5, and then 30 mL of methylene chloride was added, and the organic solvent in the reactant was separated and concentrated. 0.33 g of a blue light-emitting organic compound was synthesized by column separation (yield: 30%).

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, after mixing 9,10-di (2-naphthyl) anthracene as a host and the blue light emitting compound synthesized in Example 2 as a dopant (mixing amount: 5% by weight), to a thickness of 300 kPa The Alq3 was deposited to a thickness of 200 kPa as an electron transporting layer on the organic light emitting layer thus formed. Further, an organic light emitting diode was manufactured by forming an electron injection layer by vacuum depositing LiF to a thickness of 10 μm on the electron transport layer, and forming a cathode by depositing Al to 1200 μm thickness on the electron injection layer. On the other hand, the electroluminescent wavelength (EL), photoluminescence wavelength (Photoluminescence, PL) of the organic light emitting diode manufactured using the compound of Example 2 was measured and shown in Table 1 below.

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

As described above, the blue light emitting organic compound according to the present invention is not only excellent in heat resistance, thermal stability, film forming processability, and luminous efficiency, but also has an advantage of displaying blue light emission of high quality and various wavelengths depending on substituents. The blue light emitting organic compound according to the present invention is particularly useful for the production of full color organic light emitting diodes, and includes field effect transistors, photodiodes, photovoltaic cells, solar cells, and organic lasers. (Organic Laser), laser diode (Laser Diode) and the like can be widely applied to the manufacture of various semiconductor devices.

Claims (6)

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

In Formula 1,-(K ₁ ) _n -is a single bond direct linking group,-(alkylene) n-, -O- or -S- is a linking group, n is 1 or 2, R ₁ to R ₈ is Each independently is hydrogen, halogen, cyano, substituted or unsubstituted amino group, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol or substituted or unsubstituted alkoxy, R ₉ and Each R ₁₀ is independently hydrogen, halogen, cyano, substituted or unsubstituted amino group, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol or substituted or unsubstituted alkoxy. The blue light emitting organic compound of claim 1, wherein R ₁ to R ₁₀ combine with adjacent backbone carbon to form at least one ring, or combine with adjacent groups to form at least one ring. According to claim 1, wherein the alkyl represented by R ₁ to R ₈ is alkyl having 1 to 20 carbon atoms, the alkyl represented by R ₉ and R ₁₀ is alkyl having 1 to 20 carbon atoms, aryl is amino aryl or hetero aryl It is a blue light emitting organic compound. The method of claim 1, wherein the blue light emitting organic compound

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Blue light emitting organic 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,-(K ₁ ) _n -is a single bond direct linking group,-(alkylene) n-, -O- or -S- is a linking group, n is 1 or 2, R ₁ to R ₈ is Each independently is hydrogen, halogen, cyano, substituted or unsubstituted amino group, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol or substituted or unsubstituted alkoxy, R ₉ and Each R ₁₀ is independently hydrogen, halogen, cyano, substituted or unsubstituted amino group, substituted or unsubstituted alkyl, substituted or unsubstituted aryl, substituted or unsubstituted alcohol or substituted or unsubstituted alkoxy. 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 transport layer, and an electron transport layer.

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