KR20050099112A - Organic electroluminescence device and method for producing polyimide containing metal phthalocyanine - Google Patents

Abstract

An organic electroluminescent device in which a polyimide containing metal phthalocyanine is applied as a charge transport layer is disclosed. Polyimide containing metal phthalocyanine has excellent thermal stability and improves the properties of the organic light emitting device.

Description

Organic electroluminescence device and method for producing polyimide containing metal phthalocyanine

The present invention relates to an organic electroluminescent device, and more particularly, to an organic electroluminescent device in which a compound obtained by copolymerizing a polyimide having excellent thermal properties with a metal phthalocyanine having excellent thermal properties and charge injection and transport ability is synthesized. And a method for producing a metal phthalocyanine-containing polyimide.

Organic electroluminescence device, one of the most popular thin film display technologies, utilizes the property that the charge injected from the anode and the electron injected from the cathode combine and emit light in the light emitting layer.

The organic electroluminescent device has a method of increasing luminous efficiency by stacking a charge injection layer and a charge transport layer between an anode and a light emitting layer to lower the work function of the anode to facilitate the introduction of electric charges. There is also a method of improving the efficiency of the organic electroluminescent device by introducing an electron transport layer between the light emitting layers to facilitate electron transport.

The charge injection layer and the charge transport layer not only have a function of transferring charges transferred from the anode to the light emitting layer, but also a plurality of charges are injected into the light emitting layer at a low electric field, and electrons introduced from the cathode or the electron injection layer are trapped in the light emitting layer, thereby emitting light efficiency. This improved organic electroluminescent device can be made.

As the charge transport layer of such an organic electroluminescent device, many kinds of triamine derivatives, which are monomolecular materials, for example, N, N'-di (3-phenyl) -4,4'-diaminophenyl (hereinafter TPD) However, monomolecular materials have a problem of device life due to low thermal stability.

Triamine derivatives which have been improved through many patents, for example N, N'-di (1-naphthyl) -N, N'-diphenyl-4,4'-diaminophenyl (hereinafter NPD) and One type of star burst amine derivative, 4,4 ', 4 "-tris [N-93-methylphenyl) -N-phenylamino] triphenylamine (hereinafter referred to as MTDTTA), has been developed as a charge transport layer.

In addition, in order to improve the thermal stability of a single molecule, a polyimide resin having excellent thermal stability was used as a matrix (host) and a charge transport material (dopant) was dispersed to improve thermal stability. However, in this case, it is true that the fundamental heat resistance improvement of the single molecule dopant is limited.

In order to solve this problem, a metal phthalocyanine having excellent heat resistance and charge injection and transport ability is introduced into a polyimide backbone having excellent thermal stability, thereby developing an organic electroluminescent device having improved durability.

Therefore, an object of the present invention is to introduce a polyimide copolymer synthesized by bonding with a fluorine-containing dianhydride as a charge transport layer to overcome the heat resistance problems of existing monomolecular compounds and improve the durability of the device to improve the luminous efficiency It is to provide an organic electroluminescent device.

Other objects and features of the present invention will be more clearly understood from the embodiments described below.

In order to achieve the above object, in the present invention, a polyimide containing metal phthalocyanine is synthesized and introduced into the charge transport layer on the ITO anode, and the light emitting layer is vacuum-deposited thereon, and then a metal electrode (cathode) is deposited to form an organic electroluminescence. Manufacture the device.

To synthesize polyimide copolymer, it is a phthalocyanine derivative which has a charge injection ability, a major transport ability, an imidization reaction, and a functional group having solubility in an organic solvent. Di or tetracarboxylic hydride phthalocyanine, di or tetraamino phthalocyanine There is this.

Two functional groups have a linear imide reaction and good solubility in a solvent. However, they are difficult to control to have exactly two functional groups in the synthesis of starting materials, and the purification is also difficult, resulting in poor yield. In the case of four functional groups, the solubility decreases due to the network structure, but the thermal properties are relatively good, and the starting material is a single compound, which facilitates copolymerization control.

In the present invention, tetraamino phthalocyanine in which one amine is substituted in each of the four benzene rings of metal phthalocyanine is prepared as an amine monomer of polyimide. At this time, the substituted metal is copper, cobalt, zinc, nickel and the like, but is preferably copper and cobalt.

Examples of the diamino compound to copolymerize include 4,4'-oxy dianiline (ODA), 2,4,5,6-tetramethyl-1,4-phenylene-diamine (4MPDA), p-phenylene diamine, 2, 2'-bis (3-aminophenoxy) benzene (APB), 2,2'-bis (4-diaminophenyl) hexafluoropropane (6FDAM), and the like, preferably 2,4,5,6 Tetramethyl-1,4-phenylene-diamine (4MPDA) may be applied.

In addition, as dianhydride, 2,2-bis (3,3-dicarboxyphenyl) hexafluoropropane dianhydride (hereinafter 6FDA), 1,2,4,5-tetracarboxy benzene dianhydride (PMDA) , 3,4,4 ', 4'-benzophenone tetracarboxylic dianhydride ((BTDA), 1,2,4,5-tetracarboxy benzene dianhydride (PMDA), 3,3,3', 4'-biphenyl tetracarboxylic dianhydride (BPDA) and the like, preferably 2,2-bis (3,3-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) can be applied.

Using the above monomers, dianhydride dianhydride is added and reacted in dimethyl sulfonide under a nitrogen stream to form a polyamic acid. The temperature is reacted at room temperature between 100 ° C. and a suitable range is 60 ° C. at room temperature, preferably around 40 ° C. The polyamic acid thus prepared may be thermally cured and imidized, or imidized by a chemical method using a catalyst.

According to the present invention, since the dianhydride or diamine containing a considerable amount of fluorine is used in the manufacture of the organic electroluminescent device, it is possible to dissolve in a strong solvent such as NMP even after imidization, so that the resulting polyamic acid is imide by chemical method instead of thermosetting. (See Formula 1).

R1 is 2,2-bis (3,3-dicarboxyphenyl) hexafluoropropane, 1,2,4,5-tetracarboxy benzene, 3,4,4 ', 4'-benzophenone tetracarboxyl, 1,2,4,5-tetracarboxylic benzene, 3,3,3 ', 4'-biphenyl tetracarboxylic, etc.

Ar is 4,4'-oxy diphenyl, 2,4,5,6-tetramethyl-1,4-phenylene, p-phenylene diamine, etc.

1 is a cross-sectional view showing an organic electroluminescent device according to the present invention.

First, the polyimide prepared above was spin-coated on the cleanly washed ITO substrate 10 and then a thin film was coated, followed by soft baking at 80 ° C. for 3 hours, followed by drying under a nitrogen stream at 150 ° C. for 10 hours to form a charge transport layer 20. ). At this time, the remaining polyamic acid is completely polyimidized. Subsequently, Alq3 is vacuum deposited to form a light emitting layer 30, and Al is formed as a cathode 40 using a metal to fabricate an organic electroluminescent device.

Example 1

0.72 g of 4,4'-oxy dianiline and 0.13 g Cu-tetraamino phthalocyanine are dissolved in 50 ml dimethyl sulfonate and stirred under nitrogen stream. To this slowly add 1.77 g of 6FDA. After the addition, the reaction is carried out at 40 ° C. for 24 hours under a nitrogen stream. After the reaction, 0.4 g acetic anhydride and 0.41 g of triethylamine were added, followed by continuous chemical imidization reaction at 30 ° C. for 72 hours (CuPc 6FDA-ODA PI).

Example 2

In Example 1, instead of Cu-tetraamino phthalocyanine, 0.12 g Co-tetraamino phthalocyanine was added to react to prepare a polyimide (CoPc 6FDA-ODA PI).

Example 3

0.59 g of 2,4,5,6-tetramethyl-1,4-phenylene-diamine (4MPDA) and 0.13 g Cu-tetraamino phthalocyanine are dissolved in 50 ml dimethyl sulfonate and stirred under a nitrogen stream. To this slowly add 1.77 g of 6FDA. After the addition, the reaction is carried out at 40 ° C. for 24 hours under a nitrogen stream. After the reaction, 0.4 g acetic anhydride and 0.41 g of triethylamine were added, and the chemical imidation reaction was continuously performed at 30 ° C. for 72 hours (CuPc 6FDA-4MPDA PI).

Example 4

In Example 3, 0.12 g Co-tetraamino phthalocyanine was added instead of Cu-tetraamino phthalocyanine to prepare a polyimide (CoPc 6FDA-4MPDA PI).

The characteristics of the polyimide copolymer thus prepared were summarized in [Table 1] and confirmed.

Sample CuPc 6FDA-ODA PI CuPc 6FDA -4MPDA PI CoPc 6FDA -ODA PI CoPc 6FDA -4MPDA PI Average molecular weight Mn 50,970 50,486 55,940 54,072 Mw 54,302 54,478 56,892 57,056 PDI 1.06 1.07 1.07 1.05 Thermal properties Tg (℃) 227 220 224 218 Elementalanalyses C 57.44 56.95 57.53 57.02 H 2.71 3.43 2.76 3.43 N 5.12 5.39 5.21 5.37

Application example

The prepared CuPc 6FDA-ODA PI, CoPc 6FDA-ODA PI, CuPc 6FDA-4MPDA PI, CoPc 6FDA-4MPDA PI were dissolved in dimethylformamide as well as 0.7% by weight of solids and filtered, respectively. Thin film coating for minutes.

Then soft bake at 80 ° C. for 3 minutes, followed by drying under a nitrogen stream for 10 hours in a 150 ° C. oven to form a charge transport layer. At this time, the remaining polyamic acid is completely polyimidized. Subsequently, Alq3 was formed as a light emitting layer and Al was vacuum deposited at 10 ⁻⁶ torr as a cathode to make an organic electroluminescent device.

For comparison, N-N'-diphenyl-N-N'-bis (3-methyl) -1,1'-biphenyl-4,4'-diamine (TPD) is introduced as a charge transport layer and Alq3 as a light emitting layer. And the element of the same conditions which made Al as a cathode was produced together.

As shown in Figure 2 and 3 and Table 2, the organic electroluminescent device manufactured according to the present invention can be confirmed that the initial driving voltage is low and the luminous efficiency is excellent compared to the conventional TPD introduced into the charge transport layer. have.

MT4APc I _p E _a E _g E _a Initial drive voltage HOMO LUMO (I _p -E _g ) CuPc 6FDA-ODA PI 5.24 3.32 1.65 3.59 7.5 V CuPc 6FDA -4MPDA PI 5.16 3.04 1.59 3.57 6 V CoPc 6FDA -ODA PI 5.20 2.94 1.7 3.50 9 V CoPc 6FDA -4MPDA PI 5.12 2.98 1.7 3.42 8 V Reference Example TPD 5.5 2.4 9.5 V

As described in detail above, the newly synthesized metal phthalocyanine-containing polyimide has excellent thermal stability and has been found to have an effect of improving the characteristics of the organic light emitting device. It is also applicable to organic photosensitive layers, solar cells and the like.

1 is a cross-sectional view showing an organic electroluminescent device according to the present invention.

2 is a voltage-current curve according to an application example of the present invention.

3 is a voltage-electroluminescent curve according to an application of the present invention.

Claims (8)

An organic electroluminescent device comprising a polyimide containing metal phthalocyanine as a charge transport layer. Mixing and stirring the metal phthalocyanine derivative and the fluorine-containing diamine; Adding fluorine-containing dianhydride to react at dimethyl sulfonate under a nitrogen stream to form a polyamic acid; And Method for producing a metal phthalocyanine-containing polyimide comprising the step of performing a polyimide by heat curing or chemical treatment of the polyamic acid. 3. The method of claim 2, wherein the metal phthalocyanine derivative comprises di or tetra carboxyanhydride phthalocyanine, di or tetraamino phthalocyanine. The method of claim 2, wherein the diamine is 4,4'-oxy dianiline (ODA), 2,4,5,6-tetramethyl-1,4-phenylene-diamine (4MPDA), p-phenylene diamine, A method for producing a metal phthalocyanine-containing polyimide comprising 2,2'-bis (3-aminophenoxy) benzene (APB) and 2,2'-bis (4-diaminophenyl) hexafluoropropane (6FDAM). The dianhydride of claim 4, wherein the dianhydride is 2,2-bis (3,3-dicarboxyphenyl) hexafluoropropane dianhydride (hereinafter 6FDA), 1,2,4,5-tetracarboxylic benzene dian Hydride (PMDA), 3,4,4 ', 4'-benzophenone tetracarboxylic dianhydride ((BTDA), 1,2,4,5-tetracarboxylic benzene dianhydride (PMDA) and 3, A method for producing a metal phthalocyanine-containing polyimide comprising 3,3 ', 4'-biphenyl tetracarboxylic dianhydride (BPDA). The method of claim 2, wherein the making of the polyamic acid is carried out at room temperature to 100 ° C. 3. The method of claim 2, wherein the chemical treatment in the polyimide step is performed by adding acetic anhydride and triethylamine to carry out the reaction. Preparing an ITO substrate; Copolymerizing a polyimide containing metal phthalocyanine and wet coating on the ITO substrate and drying to form a charge transport layer; Forming a light emitting layer on the charge transport layer; And A method of manufacturing an organic electroluminescent device comprising the step of vibrating aluminum on the light emitting layer.