Light-emitting devices

Abstract

To provide a light-emitting device with good luminous efficiency. Or, to provide a light-emitting device with a good lifespan. Or, to provide a light-emitting device with a low driving voltage. [Solution] The system has an anode, a cathode, and an EL layer located between the anode and the cathode, The EL layer comprises a hole injection layer, an emitting layer, and an electron transport layer, and the hole injection layer is the luminescent layer The electron transport layer is located between the electrode and the light-emitting layer, and is located between the light-emitting layer and the cathode. The hole injection layer comprises a first substance and a second substance, the first substance being a hole injection layer Organic compounds that have transport properties and whose HOMO level is between -5.7 eV and -5.4 eV. The second substance is a substance that exhibits electron-acceptance to the first substance, and the electron transport The layers of the light-emitting device are made of a material whose resistance decreases when an electric current is passed through them. We will provide the service.

Claims

1. It has an anode and a cathode, Between the anode and the cathode, there is a first layer, a second layer, a light-emitting layer, and a third layer. The first layer is located between the anode and the light-emitting layer. The second layer is located between the first layer and the light-emitting layer. The third layer is located between the light-emitting layer and the cathode. The first organic compound in the first layer and the second organic compound in the second layer have the same skeleton, and the skeleton has one of the following: a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. A light-emitting device in which the third organic compound in the third layer is made of a material whose resistance decreases when an electric current is passed through it.

2. It has an anode and a cathode, Between the anode and the cathode, there is a first layer, a second layer, a light-emitting layer, and a third layer. The first layer is located between the anode and the light-emitting layer. The second layer is located between the first layer and the light-emitting layer. The third layer is located between the light-emitting layer and the cathode. The first organic compound in the first layer and the second organic compound in the second layer have the same skeleton, and the skeleton has one of the following: a carbazole skeleton, a dibenzofuran skeleton, a dibenzothiophene skeleton, and an anthracene skeleton. The HOMO level of the second organic compound is deeper than the HOMO level of the first organic compound. The difference between the HOMO level of the second organic compound and the HOMO level of the first organic compound is 0.2 eV or less. The third layer is made of a material whose resistance decreases when an electric current is passed through it, thus providing a light-emitting device.

3. In claim 1 or claim 2, A light-emitting device in which the material whose resistance decreases when the aforementioned current is passed through it contains an organometallic complex of an alkali metal or alkaline earth metal.

4. In claim 1 or claim 2, A light-emitting device comprising an organic compound having electron-transporting properties and an organometallic complex of an alkali metal or alkaline earth metal, wherein the material whose resistance decreases when the current is passed through it.

5. In claim 3 or claim 4, A light-emitting device in which the organometallic complex of an alkali metal or alkaline earth metal is a metal complex having a ligand containing nitrogen and oxygen, and an alkali metal or alkaline earth metal.

6. In any one of claims 3 to 5, A light-emitting device in which the organometallic complex of an alkali metal or alkaline earth metal is a metal complex having a ligand containing an 8-hydroxyquinolinate structure and a monovalent metal ion.

7. In any one of claims 3 to 5, A light-emitting device in which the organometallic complex of an alkali metal or alkaline earth metal is a lithium complex having a ligand containing an 8-hydroxyquinolinate structure.

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