Light-Emitting Element, Light-Emitting Device, Electronic Appliance, And Lighting Device

Patent metadata

Field	Value
Publication number	US-2025160211-A1
Application number	US-202519020463-A
Country	US
Kind code	A1
Filing date	Jan 14, 2025
Priority date	Apr 20, 2012
Publication date	May 15, 2025
Grant date	—

Abstract

A light-emitting element which has low driving voltage and high emission efficiency is provided. The light-emitting element includes, between a pair of electrodes, a hole-transport layer and a light-emitting layer over the hole-transport layer. The light-emitting layer contains a first organic compound having an electron-transport property, a second organic compound having a hole-transport property, and a light-emitting third organic compound converting triplet excitation energy into light emission. A combination of the first organic compound and the second organic compound forms an exciplex. The hole-transport layer contains at least a fourth organic compound whose HOMO level is lower than or equal to that of the second organic compound and a fifth organic compound whose HOMO level is higher than that of the second organic compound.

First claim

1 . (canceled)

2 . A light-emitting device comprising:
a hole-transport layer and a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes a first organic compound, a second organic compound, and a third organic compound that converts triplet excitation energy into light emission, wherein a combination of the first organic compound and the second organic compound forms an exciplex, wherein a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound, wherein a LUMO level of the first organic compound is lower than a LUMO level of the second organic compound, wherein the hole-transport layer comprises a fourth organic compound whose HOMO level is higher than the HOMO level of the second organic compound, wherein the fourth organic compound is an aromatic amine compound or a carbazole derivative, wherein a difference between an energy value of a peak of an emission spectrum of the exciplex and an energy value of a peak of an absorption band on a lowest energy side of an absorption spectrum of the third organic compound is 0.2 eV or less, and wherein the hole-transport layer is in contact with the light-emitting layer.

3 . The light-emitting device according to claim 2 ,
wherein a T1 level of the first organic compound is higher than a T1 level of the third organic compound, and wherein a T1 level of the second organic compound is higher than the T1 level of the third organic compound.

4 . The light-emitting device according to claim 2 ,
wherein the third organic compound is an iridium complex.

5 . The light-emitting device according to claim 2 , further comprising a hole-injection layer,
wherein the hole-injection layer is in contact with one of the electrodes.

6 . The light-emitting device according to claim 5 ,
wherein the hole-injection layer comprises an aromatic amine compound.

7 . The light-emitting device according to claim 5 ,
wherein the hole-injection layer comprises a carbazole derivative.

8 . The light-emitting device according to claim 2 ,
wherein the first organic compound is a π-electron deficient heteroaromatic compound, and wherein the second organic compound is a π-electron rich heteroaromatic compound.

9 . The light-emitting device according to claim 2 ,
wherein the first organic compound is a nitrogen-containing heteroaromatic compound, and wherein the second organic compound is a carbazole derivative.

10 . The light-emitting device according to claim 2 ,
wherein the first organic compound is a nitrogen-containing heteroaromatic compound, and wherein the second organic compound is an aromatic amine compound.

11 . The light-emitting device according to claim 2 ,
wherein a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is larger than or equal to 0.3 eV, and wherein a difference between the LUMO level of the first organic compound and the LUMO level of the second organic compound is larger than or equal to 0.3 eV.

12 . A light-emitting device comprising:
a hole-transport layer and a light-emitting layer between a pair of electrodes, wherein the light-emitting layer includes a first organic compound, a second organic compound, and a third organic compound that converts triplet excitation energy into light emission, wherein a combination of the first organic compound and the second organic compound forms an exciplex, wherein a HOMO level of the first organic compound is lower than a HOMO level of the second organic compound, wherein a LUMO level of the first organic compound is lower than a LUMO level of the second organic compound, wherein the hole-transport layer comprises a fourth organic compound whose HOMO level is higher than the HOMO level of the second organic compound, wherein the fourth organic compound is an aromatic amine compound or a carbazole derivative, wherein a difference between an energy value of a peak of an emission spectrum of the exciplex and an energy value of a peak of an absorption band on a lowest energy side of an absorption spectrum of the third organic compound is 0.1 eV or less, and wherein the hole-transport layer is in contact with the light-emitting layer.

13 . The light-emitting device according to claim 12 ,
wherein a T1 level of the first organic compound is higher than a T1 level of the third organic compound, and wherein a T1 level of the second organic compound is higher than the T1 level of the third organic compound.

14 . The light-emitting device according to claim 12 ,
wherein the third organic compound is an iridium complex.

15 . The light-emitting device according to claim 12 , further comprising a hole-injection layer,
wherein the hole-injection layer is in contact with one of the electrodes.

16 . The light-emitting device according to claim 15 ,
wherein the hole-injection layer comprises an aromatic amine compound.

17 . The light-emitting device according to claim 15 ,
wherein the hole-injection layer comprises a carbazole derivative.

18 . The light-emitting device according to claim 12 ,
wherein the first organic compound is a π-electron deficient heteroaromatic compound, and wherein the second organic compound is a π-electron rich heteroaromatic compound.

19 . The light-emitting device according to claim 12 ,
wherein the first organic compound is a nitrogen-containing heteroaromatic compound, and wherein the second organic compound is a carbazole derivative.

20 . The light-emitting device according to claim 12 ,
wherein the first organic compound is a nitrogen-containing heteroaromatic compound, and wherein the second organic compound is an aromatic amine compound.

21 . The light-emitting device according to claim 12 ,
wherein a difference between the HOMO level of the first organic compound and the HOMO level of the second organic compound is larger than or equal to 0.3 eV, and wherein a difference between the LUMO level of the first organic compound and the LUMO level of the second organic compound is larger than or equal to 0.3 eV.

Assignees

• Semiconductor Energy Lab

Inventors

• Seo Hiromi
• Seo Satoshi
• Shitagaki Satoko

Classifications

• H10K2101/90

  Multiple hosts in the emissive layer · CPC title

• H10K2101/30

  Highest occupied molecular orbital [HOMO], lowest unoccupied molecular orbital [LUMO] or Fermi energy values · CPC title

• H10K2101/40

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

• H10K2101/10

  Triplet emission · CPC title

• H10K85/615

  Polycyclic condensed aromatic hydrocarbons, e.g. anthracene · CPC title