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

Patent metadata

Field	Value
Publication number	US-2017352829-A1
Application number	US-201715634175-A
Country	US
Kind code	A1
Filing date	Jun 27, 2017
Priority date	Apr 6, 2012
Publication date	Dec 7, 2017
Grant date	—

Abstract

A light-emitting element having high external quantum efficiency is provided. A light-emitting element having a long lifetime is provided. A light-emitting layer is provided between a pair of electrodes. The light-emitting layer is a stack of a first light-emitting layer, which contains at least a first phosphorescent compound, a first organic compound having an electron-transport property, and a second organic compound having a hole-transport property and is provided on the anode side, and a second light-emitting layer, which contains at least a second phosphorescent compound and the first organic compound having an electron-transport property. A combination of the first organic compound and the second organic compound forms an exciplex.

First claim

1 . (canceled)

2 . A light-emitting element comprising:
an anode; a first light-emitting layer over the anode, the first light-emitting layer comprising a first phosphorescent compound, a first organic compound, and a second organic compound; a second light-emitting layer over the first light-emitting layer, the second light-emitting layer comprising the first organic compound and a second phosphorescent compound which is not the same compound as the first phosphorescent compound; and a cathode over the second light-emitting layer, wherein a hole-transport property in the second light-emitting layer is lower than a hole-transport property in the first light-emitting layer, wherein the light-emitting element is configured to emit white light, and wherein the first organic compound and the second organic compound form an exciplex.

3 . The light-emitting element according to claim 2 , wherein an emission spectrum of the exciplex of the first organic compound and the second organic compound overlaps with an absorption band on a longest wavelength side of an absorption spectrum of the first phosphorescent compound.

4 . The light-emitting element according to claim 2 , wherein the first organic compound has an electron transport property, and the second organic compound has a hole-transport property.

5 . The light-emitting element according to claim 2 ,
wherein the first organic compound includes a quinoxaline skeleton, and wherein the second organic compound includes an aromatic amine skeleton.

6 . The light-emitting element according to claim 2 , wherein light emitted from the first light-emitting layer has a shorter wavelength than light emitted from the second light-emitting layer.

7 . The light-emitting element according to claim 2 , wherein at least one of the first phosphorescent compound and the second phosphorescent compound is an organometallic complex.

8 . The light-emitting element according to claim 2 , wherein the light-emitting element is incorporated in a light-emitting device.

9 . A light-emitting element comprising:
an anode; a first light-emitting layer over the anode; a charge generation layer over the first light-emitting layer; a second light-emitting layer over the charge generation layer; a third light-emitting layer over the second light-emitting layer; a cathode over the third light-emitting layer, wherein the charge generation layer is configured to inject electrons toward the first light-emitting layer and inject holes toward the second light-emitting layer, wherein the second light-emitting layer comprises a first phosphorescent compound, a first organic compound, and a second organic compound, wherein the third light-emitting layer comprises the first organic compound and a second phosphorescent compound which is not the same compound as the first phosphorescent compound, wherein a hole-transport property in the third light-emitting layer is lower than a hole-transport property in the second light-emitting layer, wherein the light-emitting element is configured to emit white light, and wherein the first organic compound and the second organic compound form an exciplex.

10 . The light-emitting element according to claim 9 , wherein an emission spectrum of the exciplex of the first organic compound and the second organic compound overlaps with an absorption band on a longest wavelength side of an absorption spectrum of the first phosphorescent compound.

11 . The light-emitting element according to claim 9 , wherein the first organic compound has an electron transport property, and the second organic compound has a hole-transport property.

12 . The light-emitting element according to claim 9 ,
wherein the first organic compound includes a quinoxaline skeleton, and wherein the second organic compound includes an aromatic amine skeleton.

13 . The light-emitting element according to claim 9 , wherein light emitted from the second light-emitting layer has a shorter wavelength than light emitted from the third light-emitting layer.

14 . The light-emitting element according to claim 9 , wherein at least one of the first phosphorescent compound and the second phosphorescent compound is an organometallic complex.

15 . The light-emitting element according to claim 9 , wherein the light-emitting element is incorporated in a light-emitting device.

Assignees

• Semiconductor Energy Lab

Inventors

• Seo Hiromi
• Shitagaki Satoko
• Seo Satoshi
• Ushikubo Takahiro
• Sasaki Toshiki
• Uesaka Shogo

Classifications

• C09K2211/1044

  containing two nitrogen atoms as heteroatoms · CPC title

• C09K2211/185

  of the platinum group, i.e. Os, Ir, Pt, Ru, Rh or Pd · CPC title

• C07F15/0033

  Iridium compounds · CPC title

• C09K11/06 Primary

  containing organic luminescent materials · CPC title

• C09K2211/1007

  Non-condensed systems · CPC title