KR100782135B1 - Blue luminescent organic compound and organic light-emitting diode including the same - Google Patents

Abstract

Disclosed are an organic light emitting compound having high efficiency and high quality blue light and excellent thermal stability, and an organic light emitting diode including the same. The organic light emitting compound is represented by 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 organic light emitting compound, and the first and second electrodes. At least one organic compound layer located between the.

In the above formula, R _{One To} R _{6 It} may be the same or different from each other, H, CN, CO ₂ R, OR, SR, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted C 2 to 10 Alkenyl group, substituted or unsubstituted aryl group having 4 to 30 carbon atoms, heteroaryl group, cyclic group, heterocyclic group or condensed polycyclic group, wherein R is hydrogen, halogen, substituted or unsubstituted C1 to An alkyl group of 20, a substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 30 carbon atoms, a heteroaryl group, a cyclic group, a heterocyclic group or a condensed polycyclic group.

Blue light emission, organic light emitting compound, organic light emitting diode, heat resistance

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 blue organic light emitting compound and an organic light-emitting diode (OLED) including the same. More particularly, the present invention relates not only to excellent thermal stability, but also useful for forming a hole and an electron injection / transport layer. An organic light emitting compound and an organic light emitting diode comprising the same.

Organic light emitting diodes, also commonly referred to as EL (Electroluminescence device), are representative flat panels with Liquid Crystal Display (LCD), Plasma Display Panel (PDP), Field Emission Display (FED), etc. As one of the display devices, a backlight for emitting light is not required, and a device may be manufactured in a thin film and a bendable form, and pattern formation and mass production by a film fabrication technique may be easily performed. 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 When the electrons combine in the organic light emitting layer, the organic light emitting layer uses the property of generating light. Various organic compounds for forming such an organic light emitting layer are known, for example, US Patent No. 6,455,720 discloses a 2,2- (diaryl) vinylphosphine-based light emitting compound In addition, Korean Patent Publication No. 2002-70333 discloses a blue light emitting compound in which a central portion has a diphenylanthracene structure and an aryl group is substituted at the terminal. However, such a conventional blue organic light emitting compound has a disadvantage in that heat resistance is not sufficient, control of the emission color is not easy, or the synthesis process is complicated. In addition, US Pat. Nos. 5,130,603 and 6,251,531 disclose an arylene-based and anthracene-based blue light emitting compounds, respectively, but the compounds also have a disadvantage in that thermal stability such as heat resistance is not sufficient and the lifespan of the organic light emitting device using the same is reduced. .

Accordingly, an object of the present invention is to provide a blue 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 an organic light emitting compound useful for the formation of a hole and an electron injection / transport layer and an organic light emitting diode comprising the same.

In order to achieve the above object, the present invention provides a blue organic light emitting compound represented by the following formula (1). The present invention also includes a first electrode having a high work function, a second electrode having a low work function, and the organic light emitting compound, and including at least one organic compound layer positioned between the first and second electrodes. It provides an organic light emitting diode. 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, and the organic light emitting compound may be used as a host or dopant material of the light emitting layer.

[Formula 1]

In the above formula, R _{One To} R _{6 It} may be the same or different from each other, H, CN, CO ₂ R, OR, SR, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted C 2 to 10 Alkenyl group, substituted or unsubstituted aryl group having 4 to 30 carbon atoms, heteroaryl group, cyclic group, heterocyclic group or condensed polycyclic group, wherein R is hydrogen, halogen, substituted or unsubstituted C1 to An alkyl group of 20, a substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 30 carbon atoms, a heteroaryl group, a cyclic group, a heterocyclic group or a condensed polycyclic group.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The organic light emitting compound according to the present invention is a tetra-phenyl ethylene derivatives having a charge injection / transport characteristics such as electrons, holes or the like by receiving energy generated by the recombination of electron-holes, It has a structure of 1.

Wherein, R ₁ to R ₆ may be the same as or different from each other, H, CN, CO ₂ R, OR, SR, substituted or unsubstituted C1-20, preferably C1-10 alkyl, substituted Or an unsubstituted alkenyl group having 2 to 10 carbon atoms, a substituted or unsubstituted aryl group having 4 to 30 carbon atoms, preferably having 6 to 24 carbon atoms, heteroaryl group, cyclic group, heterocyclic group or condensed polycyclic group ( fused ring), wherein R is hydrogen, halogen, substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms, substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, substituted or unsubstituted And an aryl group, heteroaryl group, cyclic group, heterocyclic group or condensed polycyclic group having 4 to 30 carbon atoms, preferably 6 to 24 carbon atoms. In addition, the adjacent R ₁ and R ₂ , and R ₄ and R ₅ may be connected to each other to form a ring, for example, a condensed polycyclic group, and the condensed polycyclic group may be a naphthyl group, anthracene group, or the like. It can be illustrated.

As the substituent which may be substituted with the R ₁ to R ₆ is an aryl group or aryloxy group having 1 to 24 alkyl group, a C 1 -C 20 alkoxy group, having 6 to 30 carbon atoms in the alkyl tiok group having 1 to 20 carbon atoms , An arylthioxy group having 6 to 30 carbon atoms, an arylalkyl group having 7 to 30 carbon atoms, a monocyclic group having 5 to 30 carbon atoms, a condensed polycyclic group having 10 to 30 carbon atoms, a heterocyclic group having 5 to 30 carbon atoms, and a 4 to 40 carbon atoms Alkenyl groups, and the like, and the substituents may be further substituted with other substituents similar to the substituents.

Specific examples of the blue light emitting compound represented by Chemical Formula 1 may include the following compounds.

(1),

(2),

(3),

(One),

(2),

(3),

(4),

(5),

(6),

(4),

(5),

(6),

(7),

(8),

(9),

(7),

(8),

(9),

(10),

(11),

(12),

10,

11,

12,

(13),

(14),

(15),

(13),

14,

15,

(16),

(17),

(18)

16,

(17),

(18)

In the blue organic light emitting compound according to the present invention, since the emission wavelength and the electron / hole injection / transport characteristic change according to the type of the substituent substituted by the compound represented by Chemical Formula 1, the desired emission wavelength and charge are selected by appropriately selecting the substituent. The organic compound layer which has physical properties, such as a transfer characteristic, can be formed. The blue light emitting compound according to the present invention is excellent in heat resistance and not only improves the lifespan and productivity of the organic light emitting device, but also emits blue light with high efficiency and high quality. The blue organic light emitting compound according to the present invention can be prepared by various conventional organic synthesis methods, for example, can be prepared by the polycondensation reaction of halogen and boronic acid groups, as shown in the examples.

1 is a cross-sectional view of an organic light emitting diode according to an exemplary 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. The light emitting layer 14 including the organic light emitting compound according to the present invention is formed on the first electrode 12 and formed as a hole injection electrode (anode). In addition, the light emitting layer 14 may include a conventional host, a conventional light emitting compound, a fluorescent dye, and / or a dopant together with the organic light emitting compound according to the present invention. When the luminescent 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 content of tart is preferably 1 to 20% by weight, more preferably 5 to 10% by weight, based on the entire host / dopant. 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), or the like, and the second electrode 16 may be formed of a metal such as Al, Mg, Ca, or LiAl, It may be made of a metal alloy such as Mg-Ag.

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 emitted. The hole injection and transport layers 21 and 22 and the electron injection and transport layers 25 and 26 are further formed so as to be easily injected into 14, which is different from the organic light emitting diode shown in FIG. The hole injection and transport layers 21 and 22 have a function of facilitating injection of holes generated from the hole injection electrode 12 and a function of stably transporting holes, and the hole injection layer 21 is not limited. Porphyrinic compounds such as phthalocyanine copper, m-MTDATA (4,4 ', 4 "-tris (3-methylphenylphenylamino) triphenylamine), etc., disclosed in US Pat. No. 4,356,429, 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) is a function that facilitates the injection of electrons generated from the electron injection electrode 16 and the electrons As a function of transporting carefully, conventional electron injection and transport compounds such as, but not limited to, chinoline derivatives, particularly tris (8-quinolinorate) aluminum (aluminaquinone, Alq3), LiF, and the like, may be used to transport the electron transport 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, and to improve luminous efficiency. ), The hole injection and transport layers 21 and 22 and the electron 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, a spin coating method, or the like, which is commonly used for fabricating an organic electroluminescent device, and may be preferably formed by a vacuum deposition method. 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. 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.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 Synthesis of Organic Light Emitting Compound

As shown in Scheme 1, 2-bromo-1,1,2-triphenylethylene and 2-bromo-1,1,2-triphenylethylene and 4,4'-dioxaborolane-biphenyl ( 4,4'-bis-triphenylvinyl-biphenyl (4,4'-bis-triphenylvinyl-biphenyl) was synthesized by reacting 4,4'-dioxaborolane-biphenyl). First, 2-bromo-1,1,2-triphenylethylene (1 g, 3.0 mmol), 4,4'-dioxaborolane-biphenyl (0.3 g, 0.74 mmol), Pd (dppf) ₂ Cl ₂ (0.036 g, 0.044 mmol) ([1,1'-Bis (diphenylphosphino) ferrocene] dichloro-palladium (II)) and saturated aqueous sodium hydrogencarbonate (excess NaHCO ₃ ) solution were added to tetrahydrofuran (THF) It was then refluxed for one day with stirring. After the reaction was completed, extraction and recrystallization with methylene chloride (MC) to give the target compound in 80% yield.

¹ H-NMR (CDCl ₃ ) δ: 7.31-7.29 (4H, m), 7.11-7.01 (34H, M)

The melting point (Tm) of the synthesized material was 297.12 ° C., which was excellent in thermal stability.

Example 2 Fabrication of Organic Light Emitting Diode

The glass substrate coated with indium tin oxide (ITO) was ultrasonically cleaned, washed again 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 500 kV, and α-NPD was vacuum deposited on the hole injection layer to form a hole transport layer on the ITO electrode. The blue organic light emitting compound synthesized in Example 1 was deposited on the hole transport layer to a thickness of 300 mW as a host, and then alumina quinone (Alq3) was deposited to a thickness of 200 mW as the electron transport layer. An electron injection layer was formed by vacuum depositing LiF to a thickness of 10 Å on the electron transport layer, and aluminum was then deposited to a thickness of 1200 에 on the upper portion of the electron injection layer to form a cathode, thereby manufacturing an organic light emitting diode. As a result of measuring the luminous efficiency of the manufactured organic light emitting diode, it was 9.35 cd / A at 40 mA / cm ² , high-quality blue light emission was shown, and excellent luminous efficiency was shown.

As described above, the blue organic light emitting compound according to the present invention is not only excellent in heat resistance, film forming processability, and luminous efficiency, but also has an advantage of showing high quality and blue light emission of various wavelengths according to substituents. The blue organic light emitting compound according to the present invention is useful for the production of full color organic light emitting diodes, and may include field effect transistors, photodiodes, photovoltaic cells, solar cells, and organic lasers. It can be widely applied to various organic semiconductor devices such as an organic laser, a laser diode.

Claims (5)

An organic light emitting compound having the structure of Formula 1. [Formula 1]

Wherein R ₁ to R ₆ may be the same as or different from each other, and are H, CN, CO ₂ R, OR, SR, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon group having 2 to 10 carbon atoms. Alkenyl group, substituted or unsubstituted aryl group, heteroaryl group, cyclic group, heterocyclic group or fused ring having 4 to 30 carbon atoms, wherein R is hydrogen, halogen, substituted or unsubstituted Alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, aryl group having 4 to 30 carbon atoms substituted or unsubstituted, heteroaryl group, cyclic group, heterocyclic group or condensed polycyclic group . According to claim 1, wherein the substituent which may be substituted in R ₁ to R ₆ is an alkyl group having 1 to 24 carbon atoms, an alkoxy group having 1 to 20 carbon atoms, an aryl group or an aryloxy group having 6 to 30 carbon atoms, 1 to 20 carbon atoms Alkylthioxy group, arylthioxy group having 6 to 30 carbon atoms, arylalkyl group having 7 to 30 carbon atoms, monocyclic group having 5 to 30 carbon atoms, condensed polycyclic group having 10 to 30 carbon atoms, heterocyclic group having 5 to 30 carbon atoms, and carbon atoms A blue organic light emitting compound selected from the group consisting of 4 to 40 alkenyl groups. 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]

Wherein R ₁ to R ₆ may be the same as or different from each other, and are H, CN, CO ₂ R, OR, SR, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, a substituted or unsubstituted carbon group having 2 to 10 carbon atoms. Alkenyl group, substituted or unsubstituted aryl group, heteroaryl group, cyclic group, heterocyclic group or fused ring having 4 to 30 carbon atoms, wherein R is hydrogen, halogen, substituted or unsubstituted Alkyl group having 1 to 20 carbon atoms, substituted or unsubstituted alkenyl group having 2 to 10 carbon atoms, aryl group having 4 to 30 carbon atoms substituted or unsubstituted, heteroaryl group, cyclic group, heterocyclic group or condensed polycyclic group . 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. The organic light emitting diode of claim 3, wherein the organic compound layer is a layer selected from the group consisting of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.

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