Light-emitting element, display device, electronic device, and lighting device

Patent metadata

Field	Value
Publication number	US-10749112-B2
Application number	US-201916385472-A
Country	US
Kind code	B2
Filing date	Apr 16, 2019
Priority date	Nov 17, 2016
Publication date	Aug 18, 2020
Grant date	Aug 18, 2020

Abstract

A light-emitting element with a lower voltage and higher emission efficiency is provided. The light-emitting element includes a first organic compound, a second organic compound, and a guest material. The LUMO level of the first organic compound is lower than the LUMO level of the second organic compound, and a difference between them is larger than 0 eV and smaller than or equal to 0.5 eV. Furthermore, the HOMO level of the first organic compound is lower than the HOMO level of the second organic compound. The guest material has a function of converting triplet excitation energy into light emission. The first organic compound and the second organic compound form an exciplex.

First claim

What is claimed is:

1. A light-emitting element comprising a light-emitting layer between a pair of electrodes,
wherein the light-emitting layer comprises a first organic compound, a second organic compound, and a guest material,
wherein a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound,
wherein a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is larger than 0 eV and smaller than or equal to 0.5 eV,
wherein a LUMO level of the first organic compound is lower than a LUMO level of the second organic compound,
wherein the guest material is capable of converting triplet excitation energy into light emission,
wherein the first organic compound and the second organic compound form an exciplex,
wherein the first organic compound comprises a first electron-transport skeleton and a first hole-transport skeleton, and
wherein the second organic compound comprises a second electron-transport skeleton and a second hole-transport skeleton.

2. The light-emitting element according to claim 1 ,
wherein the difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is larger than 0 eV and smaller than or equal to 0.3 eV.

3. The light-emitting element according to claim 1 ,
wherein the first electron-transport skeleton and the second electron-transport skeleton each comprise one or more of a π-electron deficient heteroaromatic ring, an arylborane skeleton, and a phosphine oxide skeleton, and
wherein the first hole-transport skeleton and the second hole-transport skeleton each comprise one of or both a π-electron rich heteroaromatic ring and an aromatic amine skeleton.

4. The light-emitting element according to claim 1 ,
wherein the first electron-transport skeleton is a nitrogen-containing heteroaromatic ring having 8 to 18 carbon atoms, and
wherein the second electron-transport skeleton is a nitrogen-containing heteroaromatic ring having 3 to 8 carbon atoms.

5. The light-emitting element according to claim 1 ,
wherein the first hole-transport skeleton is a π-electron rich heteroaromatic ring, and
wherein the second hole-transport skeleton is an amine skeleton.

6. The light-emitting element according to claim 1 ,
wherein the first electron-transport skeleton comprises any one of a quinoline skeleton and a quinoxaline skeleton, and
wherein the second electron-transport skeleton comprises any one of a triazine skeleton, a pyrimidine skeleton, a pyridine skeleton, and a pyrazine skeleton.

7. The light-emitting element according to claim 1 ,
wherein the second organic compound is any one of organic compounds represented by Structural Formulae (100) to (109)

8. The light-emitting element according to claim 1 ,
wherein the exciplex is capable of transferring excitation energy to the guest material.

9. The light-emitting element according to claim 1 ,
wherein an emission spectrum of the exciplex overlaps with an absorption band of the guest material on the longest wavelength side.

10. The light-emitting element according to claim 1 ,
wherein the guest material comprises iridium.

11. A display device comprising:
the light-emitting element according to claim 1 ; and
at least one of a color filter and a transistor.

12. An electronic device comprising:
the display device according to claim 11 ; and
at least one of a housing and a touch sensor.

13. A lighting device comprising:
the light-emitting element according to claim 1 ; and
at least one of a housing and a touch sensor.

Assignees

• Semiconductor Energy Lab

Inventors

• Seo Satoshi
• Takahashi Tatsuyoshi
• Takeda Kyoko
• Abe Kanta
• Suzuki Hiroki

Classifications

• H10K2101/40

  Interrelation of parameters between multiple constituent active layers or sublayers, e.g. HOMO values in adjacent layers · CPC title

• C09K11/06 Primary

  containing organic luminescent materials · CPC title

• C09K2211/1044

  containing two nitrogen atoms as heteroatoms · CPC title

• H10K50/12

  comprising dopants · CPC title

• H10K50/11 Primary

  characterised by the electroluminescent [EL] layers · CPC title