Light-emitting device comprising light-emitting elements having different optical path lengths

Patent metadata

Field	Value
Publication number	US-9287332-B2
Application number	US-201213439329-A
Country	US
Kind code	B2
Filing date	Apr 4, 2012
Priority date	Apr 8, 2011
Publication date	Mar 15, 2016
Grant date	Mar 15, 2016

Abstract

A light-emitting device and a lighting device each of which includes a plurality of light-emitting elements exhibiting light with different wavelengths are provided. The light-emitting device and the lighting device each have an element structure in which each of the light-emitting elements emits only light with a desired wavelength, and thus the light-emitting elements have favorable color purity. In the light-emitting element emitting light (λ R ) with the longest wavelength of the light with different wavelengths, the optical path length from a reflective electrode to a light-emitting layer (a light-emitting region) included in an EL layer is set to λ R /4 and the optical path length from the reflective electrode to a semi-transmissive and semi-reflective electrode is set to λ R /2.

First claim

What is claimed is:

1. A light-emitting device comprising:
a first light-emitting element including a first reflective electrode, a first transparent conductive layer being in contact with the first reflective electrode, an EL layer being in contact with the first transparent conductive layer, and a semi-transmissive and semi-reflective electrode being in contact with the EL layer; and
a second light-emitting element including a second reflective electrode, the EL layer being in contact with the second reflective electrode, and the semi-transmissive and semi-reflective electrode in contact with the EL layer;
wherein the EL layer includes a first light-emitting layer emitting light with a wavelength λ Y , and a second light-emitting layer emitting light with a wavelength λ B ,
wherein, in the first light-emitting element, an optical path length from the first reflective electrode to the first light-emitting layer is 3λ B /4 and an optical path length from the first reflective electrode to the semi-transmissive and semi-reflective electrode is λ B , and
wherein, in the second light-emitting element, an optical path length from the second reflective electrode to the second light-emitting layer is λ R /4 and an optical path length from the second reflective electrode to the semi-transmissive and semi-reflective electrode is λ R /2, where a wavelength relation of λ R >λ Y >λ B is satisfied.

2. The light-emitting device according to claim 1 ,
wherein the EL layer includes one or more of a hole-injection layer, a hole-transport layer, an electron-transport layer, and an electron-injection layer.

3. The light-emitting device according to claim 1 ,
wherein light emitted from the first light-emitting element and light emitted from the second light-emitting element have wavelengths different from each other.

4. The light-emitting device according to claim 1 ,
wherein the first and second reflective electrodes are formed using a same material.

5. An electronic appliance comprising the light-emitting device according to claim 1 .

6. A lighting device comprising the light-emitting device according to claim 1 .

7. A light-emitting device comprising:
a first light-emitting element including a first reflective electrode, a first transparent conductive layer being in contact with the first reflective electrode, an EL layer being in contact with the first transparent conductive layer, and a semi-transmissive and semi-reflective electrode being in contact with the EL layer;
a second light-emitting element including a second reflective electrode, a second transparent conductive layer being in contact with the second reflective electrode, the EL layer being in contact with the second transparent conductive layer, and the semi-transmissive and semi-reflective electrode being in contact with the EL layer; and
a third light-emitting element including a third reflective electrode, the EL layer being in contact with the third reflective electrode, and the semi-transmissive and semi-reflective electrode being in contact with the EL layer,
wherein the EL layer includes a first light-emitting layer emitting light with a wavelength λ Y and a second light-emitting layer emitting light with a wavelength λ B ,
wherein, in the first light-emitting element, an optical path length from the first reflective electrode to the first light-emitting layer is 3λ G /4 and an optical path length from the first reflective electrode to the semi-transmissive and semi-reflective electrode is λ G ,
wherein, in the second light-emitting element, an optical path length from the second reflective electrode to the second light-emitting layer is 3λ B /4 and an optical path length from the second reflective electrode to the semi-transmissive and semi-reflective electrode is λ B , and
wherein, in the third light-emitting element, an optical path length from the third reflective electrode to the first light-emitting layer is λ R /4 and an optical path length from the third reflective electrode to the semi-transmissive and semi-reflective electrode is λ R /2, where a wavelength relation of λ R >λ Y >λ G >λ B is satisfied.

8. The light-emitting device according to claim 7 ,
wherein the EL layer includes one or more of a hole-injection layer, a hole-transport layer, an electron-transport layer, and an electron-injection layer.

9. The light-emitting device according to claim 7 ,
wherein the first transparent conductive layer is thicker than the second transparent conductive layer.

10. The light-emitting device according to claim 7 ,
wherein light emitted from the first light-emitting element, light emitted from the second light-emitting element, and light emitted from the third light-emitting element have wavelengths different from each other.

11. The light-emitting device according to claim 7 ,
wherein the first, second and third reflective electrodes are formed using a same material.

12. An electronic appliance comprising the light-emitting device according to claim 7 .

13. A lighting device comprising the light-emitting device according to claim 7 .

14. A light-emitting device comprising:
a first light-emitting element including a first reflective electrode, a first transparent conductive layer being in contact with the first reflective electrode, an EL layer being in contact with the first transparent conductive layer, and a semi-transmissive and semi-reflective electrode being in contact with the EL layer; and
a second light-emitting element including a second reflective electrode, the EL layer being in contact with the second reflective electrode, and the semi-transmissive and semi-reflective electrode being in contact with the EL layer,
wherein the EL layer includes a first light-emitting layer emitting light with a wavelength λ Y and a second light-emitting layer emitting light with a wavelength λ B ,
wherein, in the first light-emitting element, an optical path length from the first reflective electrode to the first light-emitting layer is 3λ G /4 and an optical path length from the first reflective electrode to the semi-transmissive and semi-reflective electrode is λ G , and
wherein, in the second light-emitting element, an optical path length from the second reflective electrode to the second light-emitting layer is λ R /4 and an optical path length from the second reflective electrode to the semi-transmissive and semi-reflective electrode is λ R /2, where a wavelength relation of λ R >λ Y >λ G >λ B is satisfied.

15. The light-emitting device according to claim 14 , wherein the EL layer includes a hole-injection layer, which comprises a composite of an organic compound and a metal oxide.

16. An electronic appliance comprising the light-emitting device according to claim 14 .

17. A lighting device comprising the light-emitting device according to claim 14 .

18. The light-emitting device according to claim 1 ,
wherein the wavelength λ Y is from 550 nm to 570 nm,
wherein the wavelength λ G is from 500 nm to 550 nm, and
wherein the wavelength λ B is from 420 nm to 480 nm.

19. The light-emitting device according to claim 7 ,
wherein the wavelength λ R is from 600 nm to 760 nm,
wherein the wavelength λ Y is from 550 nm to 570 nm,
wherein the wavelength λ G is from 500 nm to 550 nm, and
wherein the wavelength λ B is from 420 nm to 480 nm.

20. The light-emitting device according to claim 14 ,
wherein the EL layer includes one or more of a hole-injection layer, a hole-transport layer, an electron-transport layer, and a

Assignees

• Hatano Kaoru
• Semiconductor Energy Lab

Inventors

• Hatano Kaoru

Classifications

• H10K59/876 Primary

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

• H10K59/80518

  Reflective anodes, e.g. ITO combined with thick metallic layers · CPC title

• H10K50/17

  Carrier injection layers · CPC title

• H10H20/83

  Electrodes · CPC title

• H01L2251/558

  Electricity · mapped topic