Light-emitting device and display device

• US 10,461,134 B2
• Filed: 03/28/2018
• Issued: 10/29/2019
• Est. Priority Date: 02/11/2011
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Sasaki, Toshiki, Ohsawa, Nobuharu, Ushikubo, Takahiro, Yamazaki, Shunpei
• Primary Examiner(s): Kim, Su C
• Application Number:
  US15/938,498
• Publication Number:
  US 20180219048A1
• Time in Patent Office: 580 Days
• CPC Class Codes: H01L 27/15 including semiconductor components having potential barriers, specially adapted for light emission
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating
• CPC Class Codes: H10K 10/80 Constructional details
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 30/80 Constructional details
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/818 Reflective anodes, e.g. ITO combined with thick metallic layers
• CPC Class Codes: H10K 50/82 Cathodes
• CPC Class Codes: H10K 50/852 comprising a resonant cavity structure, e.g. Bragg reflector pair
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]

Abstract

A technique of manufacturing a display device with high productivity is provided. In addition, a high-definition display device with high color purity is provided. By adjusting the optical path length between an electrode having a reflective property and a light-emitting layer by the central wavelength of a wavelength range of light passing through a color filter layer, the high-definition display device with high color purity is provided without performing selective deposition of light-emitting layers. In a light-emitting element, a plurality of light-emitting layers emitting light of different colors are stacked. The closer the light-emitting layer is positioned to the electrode having a reflective property, the shorter the wavelength of light emitted from the light-emitting layer is.

Claims

1. A display device comprising:

a first light-emitting element comprising;

a first electrode that is reflective;

a first light-emitting layer;

a second light-emitting layer over the first light-emitting layer; and

a second electrode;

a second light-emitting element comprising;

a third electrode that is reflective;

the first light-emitting layer;

the second light-emitting layer over the first light-emitting layer; and

the second electrode;

a first color filter overlapping with the first light-emitting element and having a first central wavelength of a first wavelength range in which the first color filter has a transmittance of 50% or higher in a visible wavelength range; and

a second color filter overlapping with the second light-emitting element and having a second central wavelength of a second wavelength range in which the second color filter has a transmittance of 50% or higher in the visible light range,

wherein the first wavelength range is different from the second wavelength range,

wherein the first central wavelength is different from the second central wavelength, and

wherein a first optical path length between the first light-emitting layer and the first electrode is different from a second optical path length between the second light-emitting layer and the third electrode in accordance with the difference between the first central wavelength and the second central wavelength.

2. The display device according to claim 1, wherein the first optical path length is different from a third optical path length between the first light-emitting layer and the third electrode.

3. The display device according to claim 2, wherein the first optical path length is shorter than the third optical path length.

4. The display device according to claim 1, wherein an emission peak of light emitted from the first light-emitting layer is shorter than an emission peak of light emitted from the second light-emitting layer.

5. The display device according to claim 1,

wherein the first optical path length is one-quarter of the first central wavelength, and

wherein the second optical path length is m-quarters of the second central wavelength, in which m is an odd number of three or more.

6. The display device according to claim 1, comprising a charge generation layer between the first light-emitting layer and the second light-emitting layer.

7. A display device comprising:

a first light-emitting element comprising;

a first electrode that is reflective;

a first light-emitting layer;

a second light-emitting layer over the first light-emitting layer;

a third light-emitting layer over the second light-emitting layer; and

a second electrode;

a second light-emitting element comprising;

a third electrode that is reflective;

the first light-emitting layer;

the second light-emitting layer over the first light-emitting layer;

the third light-emitting layer over the second light-emitting layer; and

the second electrode;

a third light-emitting element comprising;

a fourth electrode that is reflective;

the first light-emitting layer;

the second light-emitting layer over the first light-emitting layer;

the third light-emitting layer over the second light-emitting layer; and

the second electrode over the third light-emitting layer;

a first color filter overlapping with the first light-emitting element and having a first central wavelength of a first wavelength range in which the first color filter has a transmittance of 50% or higher in a visible wavelength range;

a second color filter overlapping with the second light-emitting element and having a second central wavelength of a second wavelength range in which the second color filter has a transmittance of 50% or higher in the visible light range; and

a third color filter overlapping with the third light-emitting element and having a third central wavelength of a third wavelength range in which the third color filter has a transmittance of 50% or higher in the visible wavelength range,

wherein the first wavelength range is different from the second wavelength range,

wherein the first central wavelength, the second central wavelength, and the third central wavelength are different from one another, and

wherein a first optical path length between the first light-emitting layer and the first electrode is different from a second optical path length between the second light-emitting layer and the third electrode in accordance with the difference between the first central wavelength and the second central wavelength.

8. The display device according to claim 7, wherein a third optical path length between the first light-emitting layer and the fourth electrode is different from the first optical path length and the second optical path length.

9. The display device according to claim 7, wherein the first optical path length is different from a fourth optical path length between the first light-emitting layer and the third electrode.

10. The display device according to claim 9, wherein the first optical path length is shorter than the fourth optical path length.

11. The display device according to claim 7, wherein an emission peak of light emitted from the first light-emitting layer is shorter than an emission peak of light emitted from the second light-emitting layer.

12. The display device according to claim 7,

wherein the first optical path length is one-quarter of the first central wavelength, and

wherein the second optical path length is m-quarters of the second central wavelength, in which m is an odd number of three or more.

13. The display device according to claim 7, comprising a charge generation layer between the first light-emitting layer and the second light-emitting layer.