KR20040025986A - Luminescent spiro compound and organic light-emitting device comprising the same - Google Patents

Abstract

PURPOSE: Provided are a spiro compound emitting high elegant blue light and excellent in light emitting efficiency, heat resistance, and stability and an organic light emitting device containing the spiro compound. CONSTITUTION: The spiro compound is represented by the formula 1, wherein a connection body L is a functional group capable of forming a connection ring of more than dimer or N, B, C, P, or Si atom having at least two connection positions, R1 to R4 are identically or differently hydrogen or substituted or unsubstituted C1-C10 alkyl or alkoxy, or C1-C16 aryl, aryl amine, alkyl amine, or heteroaryl, R5 is hydrogen or substituted or unsubstituted C1-C10 alkyl, alkoxy, or amine, and n, m, o, p are integers of 0-4. And the organic light emitting device contains a first electrode having a high work function, a second electrode having a low work function, and at least one organic compound layer placed between the first and the second electrodes and containing the spiro compound.

Description

Luminescent spiro compound and organic light-emitting device comprising the same

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiro compound, and more particularly, to a spiro compound having a high-quality blue light emission, and having excellent luminous efficiency, heat resistance, and film forming process, and to an organic light-emitting device (OLED) including the same. It is about.

An organic light emitting device, commonly referred to as an EL (Electroluminescence device), is a representative flat panel display including a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), and the like. As one of the devices, there is no need for a backlight for light emission, the device can be manufactured in a thin film and a bendable form, and there is an advantage in that the pattern formation and mass production by the film production technology are easy. 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 device forms an organic light emitting layer that exhibits strong light emission 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. When the organic light emitting layer is bonded to the organic light emitting layer, the organic light emitting layer generates light. As one of materials for forming an organic light emitting layer of such an organic light emitting device, a spiro compound is known. For example, US Pat. No. 5,840,217 discloses spiro-triphenylamine, spiro. -TPD (spiro-N, N'-diphenyl-N, N'-bis (3-methylphenyl) 1,1'-biphenyl-4,4'-diamine), spiro-benzoxazole, Spyro monomolecular compounds such as spiro-sexiphenyl (spiro-sexiphenyl), spiro-DPVBi, and the like, US Patent No. 5,741,921 discloses non-carbon compounds such as spiro valence Sn, Si of the spiro compound US Pat. No. 6,211,369 discloses compounds in which at least one of the aromatic groups of the spiro compound is a heteroaryl group, and US Pat. Nos. 5,621,131 and 5,763,636 disclose spiro polymers comprising spiro compounds in repeat units. Doing. However, such a conventional spiro compound is excellent in heat resistance, but does not exhibit high efficiency of blue light emission, and is generally difficult to form a film by vacuum deposition, so that spin-coating is required to form an organic light emitting layer. There is a disadvantage to use the coating method.

Accordingly, an object of the present invention is to provide a spiro compound and an organic light emitting device including the same, which not only emit high-quality blue light but also have excellent luminous efficiency and heat resistance.

Another object of the present invention is to provide a spiro compound having excellent film forming processability and an organic light emitting device including the same.

Still another object of the present invention is to provide a spiro compound capable of forming a blue organic light emitting layer and / or an electron transport layer and an organic light emitting device including the same.

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

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

In order to achieve the above object, the present invention provides a novel spiro compound of the 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 spiro compound, and including at least one organic compound layer positioned between the first and second electrodes. An organic light emitting device is provided.

Here, the linking L is a N, B, C, P or Si atom having a functional group or two or more bonding positions capable of forming a linking ring of dimers or more, and R ₁ , R ₂ , R ₃ , and R ₄ may be the same or different from each other, hydrogen or substituted or unsubstituted alkyl or alkoxy having 1 to 10 carbon atoms, or an aryl, arylamine, alkylamine or heteroaryl group having 1 to 16 carbon atoms, and R ₅ is hydrogen or substituted Alkyl, alkoxy or amine having 1 to 10 carbon atoms, unsubstituted or substituted, n, m, o, p are integers of 0 to 4;

Here, the linkage is an aryl group containing a benzene derivative such as benzene, triphenylamine, triphenylbenzene, naphthalene, o and n is 0 or 1, p is 1, m is 2 or 3 desirable.

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

The spiro compound according to the present invention is a compound emitting light by receiving energy generated by recombination of electron-holes.

[Formula 1]

Herein, the linking body L is a functional group capable of forming a linking ring of dimer or more, or an N, B, C, P, Si atom having two or more bond positions, and preferably has two or more bond positions. Aryl group containing a benzene derivative such as benzene, triphenylamine, triphenylbenzene, naphthalene, Si or N, more preferably , , , , Si, or N.

In addition, R ₁ , R ₂ , R ₃ , and R ₄ may be the same as or different from each other, hydrogen or substituted or unsubstituted alkyl or alkoxy having 1 to 10 carbon atoms, or aryl, arylamine, alkyl having 1 to 16 carbon atoms. Amine or heteroaryl group, R ₅ is hydrogen or substituted or unsubstituted alkyl, alkoxy or amine having 1 to 10 carbon atoms, n, m, o, p are integers from 0 to 4, preferably o and n Is 0 or 1, p is 1, and m is 2 or 3.

In the present invention, a spiro compound means a compound in which two rings are bonded to one tetravalent atom, and such a tetravalent atom is called a spiro atom. Since the spiro compound according to the present invention changes the emission wavelength and charge transfer / injection characteristics according to the substituents or linkages substituted in the spyro moiety, physical properties such as desired emission wavelength, charge transfer characteristics, etc. by appropriately selecting the substituents or linkages It is possible to form an organic compound layer having a. In particular, the spiro compound according to the present invention is excellent in heat resistance and film forming processability to improve the lifespan and productivity of the light emitting device, as well as high efficiency, high-quality blue light emission, it is also useful as an electron transport layer.

The organic light emitting compound according to the present invention can be prepared by various known organic synthesis methods. Methods for the synthesis of spiro compounds are well known in the art (see JSDS July, 1978, 307, US Pat. No. 5,840,217), and the direct linkage of the linker L with the phenyl group is, for example, Suzuki-coupling: Tetrahedron Letter 1987, 5093-5096 and JOC, 1996, 61, 3127), and the vinyl group is the Wittig reaction: Vogel's Textbook of Practical Organic Chemistry ", 4th Ed., Longman. (1978) p338 and US Pat. No. 5,366,811).

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 the light emitting layer 14 containing the spiro 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 a spiro compound according to the present invention. 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 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 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 exemplary embodiment. In the organic light emitting diode illustrated in FIG. 2, holes and electrons generated in the first and second electrodes 12 and 16, respectively, are emitted from 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, such as those disclosed in Patent No. 4,356,429, for example, m-MTDATA (4,4 ', 4 "-tris (3-methylphenylamino) triphenylamine). The hole transport layer 22 includes NPB (N, N'-diphenyl-N, N'-bis (1-naphthyl) -1,1'-biphenyl) -4,4'-diamine) and triphenyldiamine derivatives. Aromatics such as styrylamine derivatives and 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 a 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 transport electrons stably As a function of the above, the spiro compound according to the present invention may be used alone or in a non-limiting manner with the conventional compounds such as chinoline derivatives, especially tris (8-quinolinorate) aluminum (aluminaquinone, Alq3). It may also be used to form the 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 thickness 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 is not particularly limited and may vary depending on the formation method, but usually has a thickness of about 5 to 500 nm. .

The organic light emitting compound according to the present invention may be included in the hole injection and transport layers 21 and 22 and / or the electron injection and transport layers 25 and 26, and the organic layers may be vacuum used for fabricating an organic electroluminescent device. The vapor deposition method, the spin coating method, and the like, and preferably the vacuum vapor deposition method. The organic light emitting compound of the present invention can be applied not only to the organic light emitting device having the structure shown in FIG. 1 or 2, but also to the organic electroluminescent device having various structures exhibiting light emission phenomenon by hole-electron coupling. The structure of such various organic light emitting devices is described, for example, in US Pat. No. 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

Reaction 1: Synthesis of 1,3,5-tri (p-bromophenyl) benzene

In order to form a linker L having a linker of at least a trimer, 1,3,5-tri (p-bromophenyl) benzene is synthesized as in Scheme 1 below.

In order to obtain 1,3,5-tri (p-bromophenyl) benzene, 3 g of 1,3,5-triphenylbenzene was first dissolved in methylene chloride, and 1.6 g of bromine was added dropwise at room temperature. After dropwise addition of bromine, the mixture was reacted at room temperature for 24 hours, followed by layer separation with water and removal of a solvent to obtain a target compound, in which the reaction proceeded quantitatively.

Reaction 2: Synthesis of 9,9'-spirobifluorene-2-boronic acid

3.9 g of bromopyribifluorene was dissolved in 50 mL of tetrahydrofuran (THF), the temperature was cooled to −90 ° C., and 40 mL of 1.6 M butyllithium was added dropwise and stirred for 5 minutes. 11 mL of trimethylborate was added dropwise to the reaction solution at -90 ° C, stirred at -78 ° C for 2 hours, and then stirred at room temperature for 12 hours. Next, 10% HCl was added dropwise at 0 ° C. to adjust the pH to 6 or less, the solvent was distilled off, and extracted with ether to give the title spiroboronic acid.

Reaction 3: Synthesis of Spyro Compounds

2.7 g of 1,3,5-tri (p-bromophenyl) benzene, the linking compound obtained in Reaction 1, 20 ml of ethyleneglycoldimethylether and 0.1 g of Pd (TPP) ₄ [Pd (triphenylphosphine) ₄ ] In a nitrogen atmosphere, the reactor was stirred at room temperature for 20 minutes, 2.5 g of boric acid was added to the spy obtained in Reaction 2, 0.5 ml of 20% Na ₂ CO ₃ aqueous solution was added thereto, and refluxed for 48 hours. After completion of the reaction, methylene chloride (MC) and water were poured to separate the layers, the solvent was distilled off, and separated by column to obtain the target compound in a yield of 30%. The reaction of 1,3,5-tri (p-bromophenyl) benzene, which is a linker compound, and spiroboric acid is summarized in the following scheme 2.

Example 2

1.5 g of the linker compound 1,3,5-tribromobenzene, 20 ml of acetone, and 0.1 g of Pd (OAc) ₂ were added to a reactor in a nitrogen atmosphere, stirred at room temperature for 20 minutes, and then in reaction 2 of Example 1 2.5 g of boric acid and 0.5 ml of 20% Na ₂ CO ₃ aqueous solution were added to the resulting spy, and the reaction was performed by refluxing for 48 hours. After completion of the reaction, methylene chloride (MC) and water was poured to separate the layers, the solvent was distilled off, and separated by column to obtain the compound of formula 2 in a yield of 20%.

Example 3

Tri (4-bromophenyl) amine was synthesized by a known method, 2.4 g of the synthesized tri (4-bromophenyl) amine was dissolved in 20 mL of acetone, and 0.1 g of Pd (OAc) ₂ was added in a nitrogen atmosphere. And stirred at room temperature for 20 minutes. Next, 2.5 g of spirobolic acid obtained in Reaction 2 of Example 1 and 0.5 ml of 20% Na 2 CO 3 aqueous solution were added thereto, and the mixture was refluxed for 12 hours to proceed with the reaction, followed by cooling. After completion of the reaction, methylene chloride (MC) and water was poured to separate the layers, the solvent was distilled off, and separated by column to obtain the compound of formula 3 in a yield of 40%.

Example 4

After dissolving 1.6 g of biphenylamine in 20 mL of toluene, tris (dibenzylideneacetone) dipalladium (0) (Tris (dibenzylideneacetone) dipalladium (0): Pd ₂ (dba) ₃ ) 0.1g, 1,1'-bis 0.2 g of (diphenylphosphino) ferrocene (1,1'-Bis (diphenylphosphino) ferrocene: DPPF) was added, 7 g of 2-bromospyrobifluorene and 4 g of t-butoxide were added. It was made to react at 90 degreeC for 10 hours. After completion of the reaction, the mixture was cooled, filtered, and water was added to separate the layers, and the solvent was concentrated. The obtained product was separated by a column to obtain a compound of formula 4 in 50% yield.

Example 5

Reaction 1: synthesis of 9,9'-spirobifluorene-4-benzaldehyde (9,9'-spirobifluorene-4-benzaldehyde)

1 mmol of 9,9'-spirobifluorene-2-boronic acid prepared in Reaction 2 of Example 1, 20 mL of acetone, 0.01 mmol of Pd (OAc) ₂ , and 4-bromo 1mmole of benzaldehyde (4-bromobenzaldehyde) is mixed and stirred, and then 1mmole of 20% Na ₂ CO ₃ is added and refluxed for 24 hours. After completion of the reaction, the solvent was concentrated, methylene chloride and water were added, and the layers were separated. The organic layer was concentrated and separated by column to obtain the title compound in a yield of 60%.

Reaction 2: Synthesis of Compound of Formula 5

1,3,5-tri (bromomethyl) benzene 1mmole and triphenylphosphine 5mmole were refluxed under a benzene solvent for 24 hours to synthesize phosphonium salts. Then filtered and dried. Next, 1 mmol of phosphonium salt, 20 mmol of 9,9'-spirobifluorene-4-benzaldehyde prepared in Reaction 1, and 2 mmol of sodium-t-butoxide (t-BuONa) were added to 20 mL of methylene chloride. The reaction is refluxed. When all the reactants disappeared, the mixture was cooled, water was added, the layers were separated, and the solvent was concentrated, and then separated by a column to obtain a compound of Chemical Formula 5, and the entire reaction process is shown in Scheme 3 below.

Example 6-10 Fabrication of Organic Light-Emitting Element

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, a hole transport layer is formed by vacuum evaporation of NPB to 150 kV on the ITO electrode, and a light emitting spiro compound synthesized in Examples 1 to 5 is vacuum deposited to 600 kW on the hole transport layer, respectively, to form an organic light emitting layer. After the formation, Alq was deposited to a thickness of 300 Å on the organic emission layer to form an electron transport layer. Finally, an organic light emitting device (Examples 5 to 10, respectively) was manufactured by forming Al on a top of the electron transport layer by depositing Al at a thickness of 2000 kV. The emission wavelength (EL) of the prepared organic light emitting device, the emission wavelength (PL: photoluminescence) of the light emitting compound in the dichloromethane (Dichloromthane) solution, and the melting point (Tm) of the light emitting compound were measured and shown in Table 1 below.

compound EL PL Tm Compound of Example 1 470 nm 425 nm 395 ℃ Compound of Example 2 430 nm 395nm 310 ℃ Compound of Example 3 495nm 455 nm 360 ℃ Compound of Example 4 465 nm 430 nm 240 ℃ Compound of Example 5 470 nm 425 nm 376 ℃

As can be seen from the above table, the EL spectrum of the organic light emitting device was shifted by 30 to 50 nm toward the longer wavelength than the PL spectrum, and the half width of the EL spectrum was about 50 to 80 nm. In addition, the external quantum efficiency (luminescence efficiency) of the manufactured organic light emitting device was 0.2 to 1.5 lm / w, the maximum emission intensity of the EL spectrum was 15000 cd / m ² .

As described above, the light emitting spiro compound according to the present invention not only has excellent heat resistance, stability and luminous efficiency, but also shows high-quality and various wavelengths of blue light depending on substituents, and has excellent film forming processability, thereby forming a film by deposition. This is an easy advantage.

Claims (5)

A spiro compound having a structure of the following formula. Here, the linking L is a N, B, C, P or Si atom having a functional group or two or more bonding positions capable of forming a linking ring of dimers or more, and R ₁ , R ₂ , R ₃ , and R ₄ may be the same or different from each other, hydrogen or substituted or unsubstituted alkyl or alkoxy having 1 to 10 carbon atoms, or an aryl, arylamine, alkylamine or heteroaryl group having 1 to 16 carbon atoms, and R ₅ is hydrogen or substituted Alkyl, alkoxy or amine having 1 to 10 carbon atoms, unsubstituted or substituted, n, m, o, p are integers of 0 to 4; The spiro compound according to claim 1, wherein the linker is selected from the group consisting of benzene, triphenylamine, triphenylbenzene, naphthalene, Si and N having two or more binding positions. The method of claim 1, wherein the linkage , , , , N and Si, wherein o and n are 0 or 1, p is 1, m is 2 or 3 spiro compound. A first electrode having a high work function; A second electrode having a low work function; And An organic light emitting device comprising a spiro compound of the following formula, and comprising at least one organic compound layer positioned between the first and second electrodes. Here, the linking L is a N, B, C, P or Si atom having a functional group or two or more bonding positions capable of forming a linking ring of dimers or more, and R ₁ , R ₂ , R ₃ , and R ₄ may be the same or different from each other, hydrogen or substituted or unsubstituted alkyl or alkoxy having 1 to 10 carbon atoms, or an aryl, arylamine, alkylamine or heteroaryl group having 1 to 16 carbon atoms, and R ₅ is hydrogen or substituted Alkyl, alkoxy or amine having 1 to 10 carbon atoms, unsubstituted or substituted, n, m, o, p are integers of 0 to 4; The organic light emitting device of claim 4, wherein the organic compound layer including the spiro compound is an organic light emitting layer or an electron transport layer formed between the second electrode and the organic light emitting layer.