Light-Emitting Element, Light-Emitting Device, Electronic Device, and Lighting Device

Patent metadata

Field	Value
Publication number	US-2016126500-A1
Application number	US-201514920281-A
Country	US
Kind code	A1
Filing date	Oct 22, 2015
Priority date	Oct 24, 2014
Publication date	May 5, 2016
Grant date	—

Abstract

To provide a novel light-emitting element or a novel light-emitting device with high emission efficiency and low power consumption, a light-emitting element having a plurality of light-emitting layers between a pair of electrodes includes a lower electrode, a first light-emitting layer over the lower electrode, a charge-generation layer over the first light-emitting layer, a second light-emitting layer over the charge-generation layer, and an upper electrode over the second light-emitting layer. An emission spectrum of the first light-emitting layer peaks at a longer wavelength than an emission spectrum of the second light-emitting layer. A distance of between a bottom surface of the upper electrode and a bottom surface of the first light-emitting layer is less than or equal to 130 nm.

First claim

What is claimed is:

1 . A light-emitting element comprising:
a lower electrode; a first light-emitting layer over the lower electrode; a charge-generation layer over the first light-emitting layer; a second light-emitting layer over the charge-generation layer; and an upper electrode over the second light-emitting layer, wherein an emission spectrum of the first light-emitting layer includes a peak at a longer wavelength than an emission spectrum of the second light-emitting layer, and wherein a distance between a bottom surface of the upper electrode and a bottom surface of the first light-emitting layer is less than or equal to 130 nm.

2 . The light-emitting element according to claim 1 ,
wherein the emission spectrum of the first light-emitting layer includes a peak in any one of a green wavelength range, a yellow green wavelength range, a yellow wavelength range, an orange wavelength range, and a red wavelength range, and wherein the emission spectrum of the second light-emitting layer includes a peak in any one of a violet wavelength range, a blue wavelength range, and a blue green wavelength range.

3 . The light-emitting element according to claim 1 ,
wherein the first light-emitting layer includes a phosphorescent material, and wherein the second light-emitting layer includes a fluorescent material.

4 . The light-emitting element according to claim 1 , wherein a distance between the bottom surface of the upper electrode and a bottom surface of the second light-emitting layer is less than 80 nm.

5 . The light-emitting element according to claim 1 , wherein a distance between a top surface of the first light-emitting layer and a bottom surface of the second light-emitting layer is less than or equal to 40 nm.

6 . The light-emitting element according to claim 1 ,
wherein the first light-emitting layer comprises a first light-emitting region at a distance of approximately λ Y /4 from the upper electrode (λ Y represents a wavelength of yellow light), and wherein the second light-emitting layer comprises a second light-emitting region at a distance of approximately λ B /4 from the upper electrode (λ B represents a wavelength of blue light).

7 . A lighting device comprising the light-emitting element according to claim 1 and a housing.

8 . A light-emitting element comprising:
a lower electrode; a hole-injection layer over the lower electrode; a first hole-transport layer over the hole-injection layer; a first light-emitting layer over the first hole-transport layer; a charge-generation layer over the first light-emitting layer; a second hole-transport layer over the charge-generation layer; a second light-emitting layer over the second hole-transport layer; an electron-transport layer over the second light-emitting layer; and an upper electrode over the electron-transport layer, wherein an emission spectrum of the first light-emitting layer includes a peak at a longer wavelength than an emission spectrum of the second light-emitting layer, and wherein a distance between a bottom surface of the upper electrode and a bottom surface of the first light-emitting layer is less than or equal to 130 nm.

9 . The light-emitting element according to claim 8 ,
wherein the emission spectrum of the first light-emitting layer includes a peak in any one of a green wavelength range, a yellow green wavelength range, a yellow wavelength range, an orange wavelength range, and a red wavelength range, and wherein the emission spectrum of the second light-emitting layer includes a peak in any one of a violet wavelength range, a blue wavelength range, and a blue green wavelength range.

10 . The light-emitting element according to claim 8 ,
wherein the first light-emitting layer includes a phosphorescent material, and wherein the second light-emitting layer includes a fluorescent material.

11 . The light-emitting element according to claim 8 , wherein a distance between the bottom surface of the upper electrode and a bottom surface of the second light-emitting layer is less than 80 nm.

12 . The light-emitting element according to claim 8 , wherein a distance between a top surface of the first light-emitting layer and a bottom surface of the second light-emitting layer is less than or equal to 40 un.

13 . The light-emitting element according to claim 8 ,
wherein the first light-emitting layer comprises a first light-emitting region at a distance of approximately λ Y /4 from the upper electrode (λ Y represents a wavelength of yellow light), and wherein the second light-emitting layer comprises a second light-emitting region at a distance of approximately λ B /4 from the upper electrode (λ B represents a wavelength of blue light).

14 . A lighting device comprising the light-emitting element according to claim 8 and a housing.

15 . A light-emitting device comprising:
a first light-emitting element emitting blue light; a second light-emitting element emitting green light; and a third light-emitting element emitting red light, the first light-emitting element comprising:
a first lower electrode;
a first transparent conductive layer over the first lower electrode;
a first light-emitting layer over the first transparent conductive layer;
a charge-generation layer over the first light-emitting layer;
a second light-emitting layer over the charge-generation layer; and
an upper electrode over the second light-emitting layer,
the second light-emitting element comprising:
a second lower electrode;
a second transparent conductive layer over the second lower electrode;
the first light-emitting layer over the second transparent conductive layer;
the charge-generation layer over the first light-emitting layer;
the second light-emitting layer over the charge-generation layer; and
the upper electrode over the second light-emitting layer, and
the third light-emitting element comprising:
a third lower electrode;
a third transparent conductive layer over the third lower electrode;
the first light-emitting layer over the third transparent conductive layer;
the charge-generation layer over the first light-emitting layer;
the second light-emitting layer over the charge-generation layer; and
the upper electrode over the second light-emitting layer,
wherein an emission spectrum of the first light-emitting layer includes a peak at a longer wavelength than an emission spectrum of the second light-emitting layer, and wherein a distance between a bottom surface of the upper electrode and a bottom surface of the first light-emitting layer is less than or equal to 130 nm.

16 . The light-emitting device according to claim 15 , further comprising:
a fourth light-emitting element emitting yellow light, the fourth light-emitting element comprising:
a fourth lower electrode;
a fourth transparent conductive layer over the fourth lower electrode;
the first light-emitting layer over the fourth transparent conductive layer;
the charge-generation layer over the first light-emitting layer;
the second light-emitting layer over the charge-generation layer; and
the upper electrode over the second light-emitting layer,
wherein a distance between the fourth lower electrode and the upper electrode is less than or equal to 130 nm.

17 . The light-emitting device according to claim 15 ,
wherein the emission spectrum of the first light-emitting layer includes a peak in any one of a green wavelength range, a yellow green wavelength range, a yellow wavelength range, an orange wavelength range, and a red w

Assignees

• Semiconductor Energy Lab

Inventors

• Uesaka Shogo
• Sasaki Toshiki
• Kataishi Riho
• Seo Satoshi

Classifications

• H10K59/876

  comprising a resonant cavity structure, e.g. Bragg reflector pair · CPC title

• H10K50/852

  comprising a resonant cavity structure, e.g. Bragg reflector pair · CPC title

• H10K50/131 Primary

  with spacer layers between the electroluminescent layers · CPC title

• H01L51/5212

  Electricity · mapped topic

• H01L51/5056

  Electricity · mapped topic