JP2000306669A - Organic luminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminescent element having high luminance light output by forming at least one of layers containing organic compound sandwitched between a pair of electrodes comprising a positive electrode and a negative electrode as a film formed from an organic compound simple substance containing one or more trialkoxysilyl groups in molecule or combination with trial koxysilane in a sol gel method. SOLUTION: An organic compound containing at least one or more trialkoxysilyl group in a molecule is preferably a hole transportation compound, a luminescent compound, or an electron transportation compound. Two or more trialkoxysilyl groups are preferably contained in an organic compound molecule, and triethoxysilyl groups or trimethoxysilyl groups are desired. An organic compound simple substance having the trialkoxysilyl groups or a sol liquid containing this organic compound and trialkoxysilane is adjusted, a sol film is formed in a spin coat method or the like, and a gel film is formed by thermal treatment. The compound is illustrated by a formula.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic light emitting device, and more particularly, to an organic light emitting device that emits light by applying an electric field to a thin film made of an organic compound.

[0002]

2. Description of the Related Art In an organic light emitting device, a thin film containing a fluorescent organic compound is sandwiched between an anode and a cathode, and electrons and holes (holes) are injected from each electrode to exciton the fluorescent compound. It is an element that utilizes light emitted when this exciton is returned to the ground state.

In 1987, a study by Kodak Company (Appl.
Phys. Lett. 51, 913 (1987)), a function-separated type using ITO as an anode, an alloy of magnesium and silver as a cathode, using an aluminum quinolinol complex as an electron transporting material and a luminescent material, and using a triphenylamine derivative as a hole transporting material. This element has a two-layer structure and is applied at a voltage of about 10 V at a voltage of 1000 cd / m ^2.
A degree of luminescence has been reported. Related patents include U.S. Pat. No. 4,539,507 and U.S. Pat.
0,432 and U.S. Pat. No. 4,885,211.

[0004] In addition, by changing the type of the fluorescent organic compound, light emission from ultraviolet to infrared can be achieved, and various compounds have recently been actively studied. For example, US Pat. No. 5,151,629 and US Pat.
409,783; U.S. Patent No. 5,382,477;
JP-A-2-247278, JP-A-3-25519
0, JP-A-5-202356, JP-A-9-
No. 2,028,782, and JP-A-9-227576.

[0005] In addition to the organic light-emitting device using the above low-molecular material, an organic light-emitting device using a conjugated polymer is also a group of Cambridge University (Nature,
347, 539 (1990)).
In this report, light emission was confirmed in a single layer by forming a film of polyphenylenevinylene (PPV) in a coating system.
Patents related to organic light-emitting devices using conjugated polymers include US Pat. No. 5,247,190 and US Pat.
No. 514,878, US Pat. No. 5,672,678,
JP-A-4-145192, JP-A-5-24746
No. 0 publication.

As described above, recent advances in organic light-emitting devices have been remarkable, and their characteristics are that high luminance, a variety of emission wavelengths, high-speed response, a thin and lightweight light-emitting device can be realized at a low applied voltage. It suggests potential for a wide range of applications.

However, at present, light output with higher luminance or higher conversion efficiency is required. In addition, there are still many problems in terms of durability such as a change with time due to long-term use and deterioration due to an atmospheric gas containing oxygen or moisture. Further, when application to a full-color display or the like is considered, emission of blue, green, and red light with good color purity is required, but this problem has not yet been sufficiently solved.

Further, a report example in which a hole transport material and a light emitting material are dispersed in a silica matrix by a sol-gel method (55th Annual Meeting of the Japan Society of Applied Physics, Vo1.
3, pl 031, Autumn 1995), but sufficient light emission characteristics have not been obtained.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an organic light-emitting device having extremely high efficiency, high brightness, and long life light output has been developed. To provide. Another object of the present invention is to provide an organic light-emitting device that has various emission wavelengths, exhibits various emission hues, and is extremely durable. Another object of the present invention is to provide an organic light emitting device that can be easily manufactured and can be manufactured at relatively low cost.

[0010]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention.

That is, the present invention provides an organic light-emitting device having at least a pair of electrodes comprising an anode and a cathode, and a layer containing one or more organic compounds sandwiched between the pair of electrodes. At least one layer is formed by a sol-gel method from a single organic compound having at least one trialkoxysilyl group in the molecule or from an organic compound having at least one trialkoxysilyl group in the molecule and alkoxysilane. An organic light-emitting device comprising a thin film.

In the present invention, by dispersing an organic compound having a charge transporting property or a light emitting property through a covalent bond in a silica matrix, a film in a very uniform dispersed state can be obtained. In addition, since the organic compound is fixed to the silica matrix, aggregation, crystallization, and the like of the organic compounds do not occur, and an organic light-emitting device that is extremely stable and has excellent durability can be provided.

[0013]

DETAILED DESCRIPTION OF THE INVENTION An organic light emitting device according to the present invention is an organic light emitting device having at least a pair of electrodes comprising an anode and a cathode and at least a layer containing one or more organic compounds sandwiched between the pair of electrodes. At least one layer of the organic compound-containing layer may be composed of an organic compound having at least one trialkoxysilyl group in the molecule or an organic compound having at least one trialkoxysilyl group in the molecule. It is characterized by comprising a film formed from silane by a sol-gel method.

In the present invention, the organic compound having at least one trialkoxysilyl group in the molecule is preferably a hole transporting compound, a luminescent compound or an electron transporting compound.

The trialkoxysilyl group includes, for example, a triethoxysilyl group, a trimethoxysilyl group, a triisopropoxysilyl group and the like.

The number of trialkoxysilyl groups contained in the molecule of the organic compound is at least one, or may be two or more, preferably 2 to 4.

The organic compound having at least one trialkoxysilyl group in the molecule is a hole transporting compound such as a triarylamine derivative, a tetraarylbiphenyldiamine derivative, a stilbene-based arylamine derivative, an oligothiophene derivative, and a polysilane derivative. And the like, in which a trialkoxysilyl group is introduced into a hole transporting compound such as Next, exemplary compounds of these representative examples are shown below. However, it is not limited to these compounds.

Illustrative compounds (hole transporting compounds)

[0019]

Embedded image

[0020]

Embedded image

[0021]

Embedded image

[0022]

Embedded image

The organic compound having at least one trialkoxysilyl group in the molecule is an electron-transporting compound such as a phenylenevinylene derivative, a benzoxazole derivative, an oxadiazole derivative, a thiadiazole derivative, a polyphenylene derivative, and a pyridine derivative. And electron transporting compounds such as pyrazine derivatives, azomethine derivatives, fluorenone derivatives, fluorenylidene derivatives, and perylene derivatives, into which trialkoxysilyl groups have been introduced. Next, exemplary compounds of these representative examples are shown below. However, it is not limited to these compounds.

Exemplary Compound (Electron Transport Material)

[0025]

Embedded image

[0026]

Embedded image

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image

The organic compound having at least one trialkoxysilyl group in the molecule is a luminescent compound such as a phenylene vinylene derivative, a condensed polycyclic aromatic derivative, a quinacridone derivative, a stilbene derivative, a coumarin derivative, and a pyran derivative. And oxazoline derivatives, porphyrin derivatives, pyrazine derivatives, organometallic complexes, perylene derivatives and the like, in which a trialkoxysilyl group is introduced. Next, exemplary compounds of these representative examples are shown below. However, it is not limited to these compounds.

Illustrative compounds (luminescent materials)

[0032]

Embedded image

[0033]

Embedded image

In the organic light-emitting device of the present invention, at least one of the layers containing the organic compound sandwiched between the anode and the cathode comprises at least one organic compound having at least one trialkoxysilyl group in the molecule. Alternatively, a film is formed by a sol-gel method from the above organic compound having at least one trialkoxysilyl group in the molecule and alkoxysilane.

As the alkoxysilane, for example, tetraethoxysilane or the like is used.

The method of forming a film by the sol-gel method is as follows.
For example, an organic compound having at least one or more trialkoxysilyl groups in the above-described molecule, or a sol solution containing the organic compound and alkoxysilane is prepared, and a spin-coating method or the like is performed using the solution of the sol solution. To form a sol film and heat-treating to form a gel film.

Further, of the organic layers, a layer containing another organic compound is formed between the anode and the cathode by a sol-gel method, a vacuum deposition method or a solution coating method. The thickness of the organic layer is 1
It is preferable to make the film thinner than 0 μm, preferably 0.5 μm or less, more preferably 0.05 to 0.5 μm.

Hereinafter, the present invention will be described in more detail with reference to the drawings. FIG. 1 is a sectional view showing an example of the organic light emitting device of the present invention. FIG. 1 shows a structure in which an anode 2, a light emitting layer 3 and a cathode 4 are sequentially provided on a substrate 1. The light-emitting element used here is useful when it has a single hole transporting ability, electron transporting ability, and luminous performance, or when a compound having each property is used as a mixture.

FIG. 2 is a sectional view showing another example of the organic light emitting device of the present invention. FIG. 2 shows a configuration in which an anode 2, a hole transport layer 5, an electron transport layer 6, and a cathode 4 are sequentially provided on a substrate 1. In this case, when the luminescent material has either the hole transporting property or the electron transporting property or a material having both functions in each layer, and is used in combination with a mere hole transporting substance having no luminescent property or an electron transporting substance Useful for In this case, the light emitting layer 3 is made of either the hole transport layer 5 or the electron transport layer 6.

FIG. 3 is a sectional view showing another example of the organic light emitting device of the present invention. FIG. 3 shows a structure in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6, and a cathode 4 are sequentially provided on a substrate 1. It separates the functions of carrier transport and luminescence, and is used in a timely combination with a compound having each property of hole transport, electron transport, and luminescence.
The degree of freedom in material selection is greatly increased, and various compounds having different emission wavelengths can be used, so that the emission hue can be diversified. Furthermore, it is possible to effectively confine each carrier or exciton in the central light emitting layer to improve the light emission efficiency.

However, FIGS. 1 to 3 show only a very basic device structure, and the structure of an organic light-emitting device using a layer of an organic compound having at least one trialkoxysilyl group in a molecule of the present invention. Is not limited to these. For example, various layer configurations such as providing an insulating layer at an interface between an electrode and an organic layer, providing an adhesive layer or an interference layer, and forming a hole transport layer from two layers having different ionization potentials can be employed.

In the present invention, the layer formed by the sol-gel method can be applied to any of a hole transporting layer, an electron transporting layer, and a light emitting layer. Compounds (for example, Tables 1 to 4 below)
4) or a luminescent compound (for example, compounds shown in Tables 5 to 8 below) or an electron transporting compound (for example, compounds shown in Tables 9 to 11 below) as necessary. Can also be used together.

[0043]

[Table 1]

[0044]

[Table 2]

[0045]

[Table 3]

[0046]

[Table 4]

[0047]

[Table 5]

[0048]

[Table 6]

[0049]

[Table 7]

[0050]

[Table 8]

[0051]

[Table 9]

[0052]

[Table 10]

[0053]

[Table 11]

In the organic light emitting device of the present invention, a layer made of an organic compound other than the layer formed by the sol-gel method is
Generally, a thin film is formed by a vacuum deposition method or a coating method by dissolving in a suitable solvent. In particular, when forming a film by a coating method, the film can be formed in combination with an appropriate binder resin.

The binder resin can be selected from a wide range of binder resins, for example, polyvinyl carbazole resin,
Polycarbonate resin, polyester resin, polyarylate resin, polystyrene resin, acrylic resin, methacrylic resin, butyral resin, polyvinyl acetal resin,
Examples include, but are not limited to, diallyl phthalate resin, phenol resin, epoxy resin, silicone resin, polysulfone resin, urea resin, and the like. These may be used alone or as a copolymer, alone or as a mixture of two or more.

The anode material preferably has a work function as large as possible. For example, a simple metal such as gold, platinum, nickel, palladium, cobalt, selenium, and vanadium or an alloy thereof, tin oxide, zinc oxide, indium tin oxide ( Metal oxides such as ITO) and indium zinc oxide can be used. Further, conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyphenylene sulfide can also be used. These electrode substances may be used alone or in combination of two or more.

On the other hand, the cathode material preferably has a small work function, such as lithium, sodium, potassium, calcium, magnesium, aluminum, indium, silver, and the like.
It can be used as a single metal or a plurality of alloys such as lead, tin and chromium. It is also possible to use metal oxidation such as indium tin oxide (ITO). Further, the cathode may have a single-layer structure or a multilayer structure.

The substrate used in the present invention is not particularly limited, but an opaque substrate such as a metal substrate or a ceramic substrate, or a transparent substrate such as glass, quartz, or a plastic sheet is used. Further, it is also possible to control the emitted light by using a color filter film, a fluorescent color conversion filter film, a dielectric reflection film or the like on the substrate.

It is to be noted that a protective layer or a sealing layer may be provided on the manufactured device for the purpose of preventing contact with oxygen, moisture, or the like. Examples of the protective layer include an inorganic material film such as a diamond thin film, a metal oxide, and a metal nitride; a polymer film such as a fluororesin, polyparaxylene, polyethylene, a silicone resin, and a polystyrene resin; and a photocurable resin. Can be Alternatively, the device itself can be covered with glass, a gas impermeable film, metal, or the like, and the element itself can be packaged with an appropriate sealing resin.

[0060]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 Indium tin oxide (ITO) formed on a glass substrate by sputtering to a thickness of 120 nm was used as a transparent conductive support substrate. This was ultrasonically washed with acetone and isopropyl alcohol (IPA) sequentially, washed with boiling IPA, and dried. Further, the substrate subjected to UV / ozone cleaning was used as a transparent conductive support substrate.

The above exemplified compound No. 0.870 g of 5,
0.230 g of tetraethoxysilane, ethanol 7.0
0 g, 1.00 g of pure water and 0.005 g of concentrated hydrochloric acid.
Stirred for hours. This was left overnight to prepare a sol solution. Using this solution, a sol film is formed on a transparent support substrate by a spin coating method (2000 rpm), left in a nitrogen atmosphere at room temperature for 8 hours, and heated at 80 ° C. for 1 hour.
Heat treatment was performed at 120 ° C. for 2 hours to form a gel film having a thickness of 70 nm.

Further, aluminum quinolinol (Al
q ₃₎ to form an electron transporting and light-emitting layer having a thickness of 50nm by vacuum deposition. The degree of vacuum during the deposition is 1.0 × 10 ⁻⁴ Pa,
The film was formed under the conditions of a film forming speed of 0.3 nm / sec.

Next, a metal layer film having a thickness of 150 nm was formed on the above-mentioned organic layer by a vacuum evaporation method using an evaporation material comprising aluminum and lithium (lithium concentration: 1 atomic%). An element having the structure shown was prepared. The degree of vacuum at the time of deposition is 1.0 × 10 ⁻⁴ Pa, and the film formation rate is 1.0 to
The film was formed under the condition of 1.2 nm / sec.

When a DC voltage of 8 V was applied to the device thus obtained with an ITO electrode as a positive electrode and an Al—Li electrode as a negative electrode, a current flowed at a current density of ^2.5 mA / cm ² , Green light emission with a luminance of 120 cd / m ² was observed.

Example 2 Indium tin oxide (ITO) formed on a glass substrate by sputtering with a thickness of 120 nm was used as a transparent conductive support substrate. This was ultrasonically washed sequentially with acetone and isopropyl alcohol (IPA), boiled and washed with IPA, and dried. Further, the substrate subjected to UV / ozone cleaning was used as a transparent conductive support substrate.

The above exemplified compound No. 14 to 0.890
g, Exemplified Compound No. 28, 0.106 g, tetraethoxysilane 0.420 g, ethanol 7.00 g,
1.00 g of pure water and 0.005 g of concentrated hydrochloric acid were mixed and stirred for 1 hour. This was left overnight to prepare a sol solution. Using this solution, a sol film is formed on a transparent support substrate by a spin coating method (2000 rpm), left at room temperature for 8 hours in a nitrogen atmosphere, and at 80 ° C. for 1 hour.
Heat treatment was performed at 20 ° C. for 2 hours to form a gel film having a thickness of 110 nm.

Next, a metal layer film having a thickness of 150 nm was formed on the above-mentioned organic layer by a vacuum evaporation method using a vapor deposition material composed of aluminum and lithium (lithium concentration 1 atomic%). An element having the structure shown was prepared. The degree of vacuum at the time of deposition is 1.0 × 10 ⁻⁴ Pa, and the film formation rate is 1.0 to
The film was formed under the condition of 1.2 nm / sec.

When a DC voltage of 13 V is applied to the device thus obtained with the ITO electrode serving as a positive electrode and the Al-Li electrode serving as a negative electrode, A current flowed at a current density of 1 mA / cm ² , and blue light emission with an initial luminance of 65 cd / m ² was observed.

Example 3 Indium tin oxide (ITO) having a thickness of 120 nm formed on a glass substrate by a sputtering method was used as a transparent conductive support substrate. This was ultrasonically washed sequentially with acetone and isopropyl alcohol (IPA), boiled and washed with IPA, and dried. Further, the substrate subjected to UV / ozone cleaning was used as a transparent conductive support substrate.

The above-mentioned exemplified compound No. 1.50 g, ethanol 7.00 g, pure water 1.00 g, concentrated hydrochloric acid 0.00
5 g were mixed and stirred for 1 hour. This was left overnight to prepare a sol solution. Using this solution, a sol film is formed on a transparent support substrate by a spin coating method (2000 rpm) and left at room temperature for 8 hours in a nitrogen atmosphere.
Heat treatment at 80 ° C for 1 hour and 120 ° C for 2 hours,
A gel film having a thickness of 55 nm was formed.

The above exemplified compound No. 29 to 0.09 l
g, 0.210 g of tetraethoxysilane, 7.00 g of ethanol, 1.00 g of pure water, and 0.005 g of concentrated hydrochloric acid, and stirred for 1 hour. This was left overnight to prepare a sol solution. Using this solution, a spin coat method (2) is applied to the transparent support substrate on which the hole transport layer is formed.
000 rpm) to form a sol film under a nitrogen atmosphere.
It was left at room temperature for 8 hours, and heat-treated at 80 ° C. for 1 hour and at 120 ° C. for 2 hours to form a gel film having a thickness of 12 nm.

The above exemplified compound No. 18 to 0.770
g, 0.210 g of tetraethoxysilane, 7.00 g of ethanol, 1.00 g of pure water, and 0.005 g of concentrated hydrochloric acid, and stirred for 1 hour. This was left overnight to prepare a sol solution. Using this solution, a sol film is formed on the transparent support substrate by a spin coating method (2000 rpm), and left at room temperature under a nitrogen atmosphere for 8 hours.
Heat treatment at 0 ° C for 1 hour and 120 ° C for 2 hours
A gel film having a thickness of nm was formed.

Next, a metal layer film having a thickness of 150 nm was formed on the organic layer by a vacuum deposition method using a deposition material composed of aluminum and lithium (lithium concentration: 1 atomic%). An element having the structure shown was prepared. The degree of vacuum at the time of deposition is 1.0 × 10 ⁻⁴ Pa, and the film formation rate is 1.0 to
The film was formed under the condition of 1.2 nm / sec.

When a DC voltage of 8 V was applied to the device thus obtained with the ITO electrode as the positive electrode and the Al-Li electrode as the negative electrode, A current flowed at a current density of 1 mA / cm ² , and yellow light emission with an initial luminance of 370 cd / m ² was observed.

[0076] Further, the device in the lower 80 ° C. nitrogen atmosphere, keeping the current density 3.0 mA / cm ^2, where a voltage was applied for 100 hours, an initial luminance 160 cd / m after ² 100 hours luminance 145cd / m ² The luminance deterioration was very small.

Comparative Example 1 The compound used in the hole transport layer of Example 1 was exemplified by Compound No. Comparative Example 1 was carried out in exactly the same manner as in Example 1, except that 4,4'-bis [N-phenyl-N- (3 "-methylphenyl) amino] biphenyl was used instead of 5 (0.870 g). Was made.

A voltage of up to 20 V was applied to the device thus obtained with the ITO electrode serving as a positive electrode and the Al-Li electrode serving as a negative electrode, but no light emission was observed at 20 V until dielectric breakdown occurred.

[0079]

As described above, the organic light-emitting device having a layer formed by a sol-gel film forming method from the organic compound having a trialkoxysilyl group alone or from the organic compound and the alkoxysilane according to the present invention, As shown in Examples and Comparative Examples, light emission with high luminance can be obtained at a low applied voltage, and the durability is excellent. Further, the device can be prepared by using a vacuum deposition method or a casting method, and a relatively inexpensive and large-area device can be easily prepared.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view illustrating another example of the organic light emitting device according to the present invention.

FIG. 3 is a cross-sectional view illustrating another example of the organic light emitting device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Light emitting layer 4 Cathode 5 Hole transport layer 6 Electron transport layer

Continuation of the front page (72) Inventor Seiji Mashimo 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 3K007 AB00 AB02 AB03 AB04 AB12 AB13 AB18 BB00 BB01 CA01 CB01 DA00 DB03 EB00 FA01

Claims (5)

[Claims] 1. An organic light-emitting element having at least a pair of electrodes including an anode and a cathode and one or more layers containing an organic compound sandwiched between the pair of electrodes, wherein at least one of the layers containing the organic compound is provided. Consists of a film formed from a single organic compound having at least one trialkoxysilyl group in the molecule or from an organic compound having at least one trialkoxysilyl group in the molecule and alkoxysilane by a sol-gel method. An organic light-emitting device, comprising: 2. The organic light emitting device according to claim 1, wherein the organic compound having at least one trialkoxysilyl group in a molecule is a hole transporting compound. 3. The organic light emitting device according to claim 1, wherein the organic compound having at least one trialkoxysilyl group in a molecule is a light emitting compound. 4. The organic light emitting device according to claim 1, wherein the organic compound having at least one trialkoxysilyl group in the molecule is an electron transporting compound. 5. The method according to claim 1, wherein the organic compound having at least one trialkoxysilyl group in the molecule has two or more groups.
The organic light-emitting device according to claim 1, wherein the organic light-emitting device is an organic compound having at least three trialkoxysilyl groups.