KR20010047942A - Organic electroluminescent device containing electro-active organic complex thin layers - Google Patents

Abstract

PURPOSE: An organic EL device including an organic composite thin film having electric activity is provided to improve heat-resistance and electric characteristic. CONSTITUTION: An organic EL device includes one or more of organic composite thin films which are formed of polyimide having electric activity and mono-molecule having electric activity. A or B having electric activity has a function selected from the group consisting of a hole filling function, a hole transmitting function, a light doping function, an electron transmitting function, and a hole controlling function.

Description

ORGANIC ELECTROLUMINESCENT DEVICE CONTAINING ELECTRO-ACTIVE ORGANIC COMPLEX THIN LAYERS}

The present invention relates to an organic electroluminescent device comprising an organic composite thin film having an electrical activity, and more specifically, to an organic layer comprising an organic composite thin film made of a mixture of a single molecule having an electrical activity and a polyimide having an electrical activity, And it relates to an organic electroluminescent device excellent in electrical properties.

Various examples of applying polyimide to organic electroluminescent devices are known. Japanese Patent Laid-Open Publication No. H3-274693, which first applied polyimide to an organic electroluminescent device, discloses an organic electroluminescent device comprising a polyimide thin film that can be molded by an evaporation method as an organic light emitting layer. Arc uses polyimide as a protective layer of an organic electroluminescent element. In addition, Japanese Patent Laid-Open No. Hei 4-93389 discloses a polyimide as an organic charge transfer layer, and Japanese Patent Laid-Open No. Hei 7-230881 discloses a pyrolytic polyimide as a hole transfer layer. However, they all deal with the main chain polyimide, and only one of the diamines and dianhydrides of the polyimide, for example, the diamine component, which is easy to synthesize, has electrical activity. Since the method is adopted, about 50% of the entire polyimide is electrically inert, so the performance of the organic electroluminescent device made by this method was limited.

In addition, Japanese Patent Application Laid-open No. Hei 9-153641 discloses a method for producing a dispersion matrix polymer thin film by simultaneously vacuum depositing a monomolecule having electrical activity but low heat resistance and dianhydride and diamine required for polyimide polymerization. . However, this method also uses a generally known insulating polyimide for stabilizing electrically active monomolecules, but the electrical properties of the finally obtained organic electroluminescent device are not very good. Although it should include a large amount of monomolecular weight of more than%, in order to obtain a uniform thin film without phase separation in reality, there is still a problem because the content ratio of monomolecule and polyimide should be limited.

Accordingly, the inventors have intensively studied and found that heat resistance is achieved by using an organic composite thin film made of a polyimide having an electrical activity formed from a single molecule having electrical activity and at least one component of diamine and dianhydride having electrical activity. And it has been found that the organic electroluminescent device excellent in electrical properties can be manufactured and completed the present invention.

An object of the present invention is to provide an organic electroluminescent device having excellent heat resistance and electrical properties.

1 is a side view showing the structure of an organic electroluminescent device manufactured according to an embodiment of the present invention,

2 is a side view showing the structure of an organic electroluminescent device manufactured according to a comparative example or an embodiment,

3 and 4 show the current density- and luminance-applied voltage characteristics of the organic electroluminescent device manufactured according to the comparative example, respectively.

5 and 6 show the current density- and luminance-applied voltage characteristics of the organic electroluminescent device manufactured according to the embodiment, respectively.

* <Description of the symbols for the main parts of the drawings>

1: flat glass 2: ITO transparent electrode layer

3: hole injection layer (HIL) 4: hole transfer layer (HTL)

5: light emitting layer (EML)

6: electron transport / hole blocking layer (ET / HBL)

7: electron transfer layer (ETL) 8: metal electrode layer

9: power

In order to achieve the above object, the present invention provides an organic electroluminescent device comprising at least one organic composite thin film composed of a monomolecule having electrical activity and a polyimide of Formula 1 having electrical activity as an organic layer:

Where

A is a moiety derived from a dianhydride compound;

B is a moiety derived from a diamine compound;

At least one of A and B has electrical activity.

Hereinafter, the present invention will be described in detail.

The monomolecule having electrical activity used in the present invention has a function selected from hole injection ability, hole transfer ability, light emission ability, light emission doping ability, electron transfer ability and hole control ability.

As a representative example, as the hole-injecting monomolecule, 4,4 ', 4 "-tris (N-3-methylphenyl-n-phenyl-amino) -triphenylamine (m-MTDATA) of the following Chemical Formula 2 and the following Chemical Formula Copper phthalocyanine (CuPc) of 3; As the hole-transporting monomolecule, N, N'-bis (phenylphenylene) -N, N'-bis (phenyl) benzidine of the following formula (4), N, N ' -Bis (3-methylphenyl) -N, N'-bis (phenyl) benzidine (TPD) and N, N'-di (naphthalen-1-yl) -N, N'-diphenylbenzidine (NPB) Or α-NPD); 2- (2-hydroxyphenyl) benzoxazolato lithium (LiPBO) of formula (7) as the light emitting monomolecular molecule, 4,4'-bis (2,2'- of formula (8) Diphenyl-ethen-1-yl) -biphenyl (DPVBi), bis (8-hydroxy-2-methylquinolinato) -aluminum biphenoxide (BAlq) of formula 9, 2- ( 2-benzotriazolyl) -p-cresol lithium (LiBTZC), tris (8-hydroxyquinolinato) alu - titanium (Alq ₃₎ and to 4- (dicyanomethylene) -2-isobutyl-6 of formula 12 (line pyrrolidine-4-yl-vinyl) -4H- pyran the (DCJTB); light-emitting dopant ability monomolecular Examples of 4,4'-bis (2- (9-ethylcarbazolyl) -ethen-1-yl) -biphenyl (BCzVBi) of formula 13, perylene of formula 14 and 9,18- of formula 15 Dihydrobenzo [h] benzo [7,8] quino [2,3-b] acridin-7,16-dione (NQCD); as an electron transport / hole blocking function single molecule, 2- ( 4-t-butylphenyl) -5- (4-biphenyl) -1,3,4-oxadiazole (B-PBD) and Bathocuproine (BCP) of formula (17):

In the polyimide used in the present invention, at least one of the constituents derived from diamine and dianhydride (A and B of Formula 1) has electrical activity, thereby having electrical activity. Specific examples of A or B having electrical activity include single molecules having the above-described electrical activity.

According to the present invention, both a wet method and a dry method are possible as a method for preparing an organic composite thin film comprising a single molecule having electrical activity and a polyimide of Chemical Formula 1 having electrical activity. In the wet method, one of the two first synthesizes a polyamic acid, which is a precursor of polyimide, by using dianhydride and diamine having at least an electrical activity, and mixes the precursor with a single molecule having electrical activity. After the spin-coating, doctor-blading or roll-coating the mixed solution to prepare a precursor thin film, and finally thermally imidates a stable organic composite thin film can be prepared. In the case of the dry process, one of the two methods is to deposit at least the dianhydride and diamine having electrical activity and the single molecule having electrical activity at the same time in a vacuum or to deposit the dianhydride and the diamine first thinly and then After repeating vapor deposition, finally, thermal imidation can produce a stable organic composite thin film. The organic composite thin film may be prepared in a thickness of 1 to 1000 nm, and the manufacturing process of the organic composite thin film is as shown in Scheme 1 below.

Where

A and B are as defined above.

According to the present invention, the diamines and dianhydrides constituting the polyimide having electrical activity, and the single molecules having electrical activity are the same or different from each other, that is, hole injection ability, hole transport ability, light emission ability, light emission doping ability. It may have an electron transport ability or a hole blocking ability, and the function of the organic composite thin film formed according to the combination of the functions is determined. The composition ratio of the polyimide and the single molecule may also be variously selected according to the desired properties. The weight ratio of the polyimide: monomer may be adjusted in a range of 98: 2 to 10:90.

The organic electroluminescent device according to the present invention includes at least one organic composite thin film as an organic layer. 1 is a side view showing a structure of an organic electroluminescent device manufactured according to an embodiment of the present invention, a flat glass (1), ITO (indium-tin-oxide) transparent electrode layer (2), hole injection layer (HIL) (3), hole transport layer (HTL) (4), light emitting layer (EML) (5), electron transport / hole blocking layer (ET / HBL) (6), electron transport layer (ETL) (7) and metal electrode layer ( 8) and driven by an alternating current or direct current voltage (9), wherein at least one of the organic layers of (3) to (7) is an organic composite thin film having electrical activity.

The organic electroluminescent device according to the present invention has excellent electrical properties such as heat resistance, high brightness, low voltage, etc. Field Effect Transistor, Photodiode, Solar cell and Photorefractive device ), And the like can be suitably used in electrical and optical devices.

The present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited only to the following examples.

Comparative example

First, on the patterned ITO / glass substrate, pyromellitic dianhydride (PMDA) of Formula 18 and N, N'-diphenyl-N, N'-bis (4-aminobiphenyl) of Formula 19 N-methyl-2-pyrrolidone (NMP) in which PMDA-DBABBD polyamic acid of the following formula (20) obtained from)-(1,1'-biphenyl) -4,4'-diamine (DBABBD) is a solvent The wt% dissolved solution was spin coated for about 3 minutes at 3,000 rpm. The precursor thin film formed was dried at 80 ° C. for about 1 hour and then thermally imidized at 200 ° C. for about 1 hour in a vacuum oven. The PMDA-DBABBD polyimide thin film of Chemical Formula 21 thus obtained was 150 Å thick, and the hole transport layer (HTL) was placed in a vacuum evaporator to deposit about 600 Å of Alq ₃ , a green light emitting material, and then to deposit Li / Al electrode at 2000 Å. The organic electroluminescent device was completed. The structure of the fabricated organic electroluminescent device is shown in FIG. 2.

3 and 4 show the current density- and luminance-applied voltage characteristics of the fabricated device, respectively. From FIG. 3, it can be seen that current flows from about 3V and as much as about 10,000 A / m ² flows at 25V. In addition, in FIG. 4, a voltage of about 6 V was required to obtain 0.1 cd / m ^2, and a voltage of about 7.5 V was required to obtain 1 cd / m ² . Accordingly, it can be seen that the current control characteristic as the main chain polyimide thin film itself is limited because a difference of about 3 V occurs between the voltage through which the current flows and the voltage at which light is emitted. Finally, up to 4,000 cd / m ² was obtained at about 25V.

Example

First, the patterned ITO / glass substrate is placed in a vacuum evaporator, and the PMDA of Formula 18, DBABBD of Formula 19, and NPB of Formula 6 are simultaneously deposited in vacuum while controlling the deposition rate so that the weight mixing ratio is 1: 1: 2. It was. The polyimide precursor of Formula 20 thus formed was thermally imidized at about 200 ° C. for about 1 hour to prepare a PMDA-DBABBD polyimide thin film of Formula 21 having a thickness of 120 μs. The polyimide hole transport layer (HTL) having electrical activity was placed in a vacuum evaporator, and Alq ₃ , which is a green light emitting material, was deposited at about 500 mW and then Li / Al electrode was deposited at 2500 mW to complete the organic electroluminescent device. The structure of the fabricated organic electroluminescent device is shown in FIG. 2.

5 and 6 show the current density- and luminance-applied voltage characteristics of the fabricated device, respectively. From FIG. 5, it can be seen that a current flows from about 2.5V and a large current flows about 2000 A / m ² at 20V. In addition, in FIG. 6, a voltage of about 3 V was required to obtain 0.1 cd / m ^2, and a voltage of about 4 V was required to obtain 1 cd / m ² . Accordingly, it can be seen that the hole injection and hole transfer ability of the organic composite thin film having electrical activity are superior to the main chain polyimide thin film because there is almost no difference between the voltage through which the current flows and the voltage at which light is emitted. Finally, high brightness of up to 15,000 cd / m ² was obtained at about 20V.

The organic electroluminescent device according to the present invention has excellent electrical properties such as heat resistance, high brightness, low voltage, etc. Field Effect Transistor, Photodiode, Solar Cell, and Photorefractive Device ), And the like can be suitably used in electrical and optical devices.

Claims (5)

An organic electroluminescent device comprising at least one organic composite thin film composed of a single molecule having electrical activity and a polyimide of formula 1 having electrical activity as an organic layer: Formula 1 Where A is a moiety derived from a dianhydride compound; B is a moiety derived from a diamine compound; At least one of A and B has electrical activity. The method of claim 1, An organic electroluminescent device characterized in that a single molecule having an electrical activity and A or B has a function selected from hole injection ability, hole transfer ability, light emission ability, light emission doping ability, electron transfer ability and hole control ability. The method according to claim 1 or 2, Monomolecules having electrical activity and A or B are 4,4 ', 4 "-tris (N-3-methylphenyl-n-phenyl-amino) -triphenylamine (m-MTDATA), copper phthalocyanine (CuPc), N , N'-bis (phenylphenylene) -N, N'-bis (phenyl) benzidine, N, N'-bis (3-methylphenyl) -N, N'-bis (phenyl) benzidine (TPD), N, N'-di (naphthalen-1-yl) -N, N'-diphenylbenzidine (NPB or α-NPD), 2- (2-hydroxyphenyl) benzoxazolato lithium (LiPBO), 4,4 ' -Bis (2,2'-diphenyl-ethen-1-yl) -biphenyl (DPVBi), bis (8-hydroxy-2-methylquinolinato) -aluminum biphenoxide (BAlq), 2- ( 2-benzotriazolyl) -p-cresol lithium (LiBTZC), tris (8-hydroxyquinolinato) aluminum (Alq ₃ ), 4- (dicyanomethylene) -2-isobutyl-6- (julolidine 4-yl-vinyl) -4H-pyran (DCJTB), 4,4'-bis (2- (9-ethylcarbazolyl) -ethen-1-yl) -biphenyl (BCzVBi), perylene, 9, 18-dihydrobenzo [h] benzo [7,8] quino [2,3-b] acridin-7,16-dione (NQCD), 2- (4-t-butylphenyl) -5- (4 -Biphenyl) -1,3,4-jade Oxadiazole (PBD-B) and an organic electroluminescent device, characterized in that one or more selected from the group consisting of (Bathocuproine, BCP) to Basso Coop. The method of claim 1, The organic composite thin film, one of which is a mixture of dianhydride having at least an electrical activity and a polyimide precursor (polyamic acid) synthesized from a diamine and a single molecule having an electrical activity, and then coating a mixed solution and thermal imidization An organic electroluminescent device characterized in that it is manufactured by. The method of claim 1, The organic composite thin film may be formed by simultaneously depositing dianhydride and diamine having at least an electrical activity and a single molecule having electrical activity in a vacuum at the same time or by depositing the dianhydride and diamine and then depositing the single molecule. After repeated, the organic electroluminescent device characterized in that it is produced by thermal imidization.