Light-emitting device and display device

• US 8,957,442 B2
• Filed: 02/08/2012
• Issued: 02/17/2015
• 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:
  US13/368,932
• Publication Number:
  US 20120205686A1
• Time in Patent Office: 1,105 Days
• Field of Search: 257/40, 257/98, 257/E33.005, 257/E33.068, 438/29, 438/35, 438/99, 362/231, 313/505
• US Class Current: 257/98
• 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 light-emitting device comprising:

a first element comprising;

a first color filter layer; and

a first light-emitting element,

wherein the first light-emitting element comprises;

a first electrode having a reflective property;

a first light-emitting layer over the first electrode having a reflective property; and

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

a second element comprising;

a second color filter layer; and

a second light-emitting element,

wherein the second light-emitting element comprises;

a second electrode having a reflective property;

a first conductive layer having a light-transmitting property over the second electrode having a reflective property;

the first light-emitting layer over the first conductive layer having a light-transmitting property; and

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

wherein a first optical path length between the first electrode having a reflective property and the first light-emitting layer in the first element is determined based on a first wavelength range in which the first color filter layer has a transmittance of 50% or higher in a visible light range,

wherein a second optical path length between the second electrode having a reflective property and the second light-emitting layer in the second element is determined based on a second wavelength range in which the second color filter layer has a transmittance of 50% or higher in the visible light range, and

wherein a wavelength of a color of light emitted from the first light-emitting layer is shorter than a wavelength of a color of light emitted from the second light-emitting layer.

2. The light-emitting device according to claim 1,

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

wherein the second optical path length is three-quarters of a second central wavelength of the second wavelength range, and

wherein the first central wavelength is shorter than the second central wavelength.

3. The light-emitting device according to claim 1, wherein the first conductive layer having a light-transmitting property comprises a material selected from a group consisting of indium oxide, indium tin oxide, an indium oxide-zinc oxide alloy, zinc oxide, zinc oxide to which gallium is added, graphene, polyaniline or a derivative thereof, polypyrrole or a derivative thereof, polythiophene (PEDOT) or a derivative thereof, and a copolymer of two or more of aniline, pyrrole, and thiophene or a derivative thereof.

4. The light-emitting device according to claim 1,

wherein the first light-emitting element further comprises a second conductive layer having a light-transmitting property between the first electrode having a reflective property and the first light-emitting layer, and

wherein the second conductive layer having a light-transmitting property has a different thickness from the first conductive layer having a light-transmitting property.

5. The light-emitting device according to claim 4, wherein the second conductive layer having a light-transmitting property comprises a material selected from a group consisting of indium oxide, indium tin oxide, an indium oxide-zinc oxide alloy, zinc oxide, zinc oxide to which gallium is added, graphene, polyaniline or a derivative thereof, polypyrrole or a derivative thereof, polythiophene (PEDOT) or a derivative thereof, and a copolymer of two or more of aniline, pyrrole, and thiophene or a derivative thereof.

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

7. The light-emitting device according to claim 1 further comprising an electrode having a light-transmitting property over the second light-emitting layer.

8. The light-emitting device according to claim 1,

wherein the first optical path length is an optical path length between a surface of the first electrode having a reflective property and a lower surface of the first light-emitting layer or more and an optical path length between the surface of the first electrode having a reflective property and an upper surface of the first light-emitting layer or less, and

wherein the second optical path length is an optical path length between a surface of the second electrode having a reflective property and a lower surface of the second light-emitting layer or more and an optical path length between the surface of the second electrode having a reflective property and an upper surface of the second light-emitting layer or less.

9. The light-emitting device according to claim 1, wherein the light-emitting device is a display device.

19. The light-emitting device according to claim 1, wherein the visible light range is 380 nm to 680 nm.

10. A light-emitting device comprising:

a first element comprising;

a first color filter layer; and

a first light-emitting element,

wherein the first light-emitting element comprises;

a first electrode having a reflective property;

a first light-emitting layer over the first electrode having a reflective property;

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

a third light-emitting layer over the second light-emitting layer,

a second element comprising;

a second color filter layer; and

a second light-emitting element,

wherein the second light-emitting element comprises;

a second electrode having a reflective property;

a first conductive layer having a light-transmitting property over the second electrode having a reflective property;

the first light-emitting layer over the first conductive layer having a light-transmitting property;

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

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

a third element comprising;

a third color filter layer; and

a third light-emitting element,

wherein the third light-emitting element comprises;

a third electrode having a reflective property;

a second conductive layer having a light-transmitting property over the third electrode having a reflective property;

the first light-emitting layer over the second conductive layer having a light-transmitting property;

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

the third light-emitting layer over the second light-emitting layer,

wherein a first optical path length between the first electrode having a reflective property and the first light-emitting layer in the first element is determined based on a first wavelength range in which the first color filter layer has a transmittance of 50% or higher in a visible light range,

wherein a second optical path length between the second electrode having a reflective property and the second light-emitting layer in the second element is determined based on a second wavelength range in which the second color filter layer has a transmittance of 50% or higher in the visible light range,

wherein a third optical path length between the third electrode having a reflective property and the third light-emitting layer in the third element is determined based on a third wavelength range in which the third color filter layer has a transmittance of 50% or higher in the visible light range,

wherein a wavelength of a color of light emitted from the first light-emitting layer is shorter than a wavelength of a color of light emitted from the second light-emitting layer,

wherein a wavelength of a color of light emitted from the second light-emitting layer is shorter than a wavelength of a color of light emitted from the third light-emitting layer, and

wherein the first conductive layer having a light-transmitting property has a different thickness from the second conductive layer having a light-transmitting property.

11. The light-emitting device according to claim 10,

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

wherein the second optical path length is three-quarters of a second central wavelength of the second wavelength range,

wherein the third optical path length is five-quarters of a third central wavelength of the third wavelength range,

wherein the first central wavelength is shorter than the second central wavelength, and

wherein the second central wavelength is shorter than the third central wavelength.

12. The light-emitting device according to claim 10,

wherein the first conductive layer having a light-transmitting property comprises a material selected from a group consisting of indium oxide, indium tin oxide, an indium oxide-zinc oxide alloy, zinc oxide, zinc oxide to which gallium is added, graphene, polyaniline or a derivative thereof, polypyrrole or a derivative thereof, polythiophene (PEDOT) or a derivative thereof, and a copolymer of two or more of aniline, pyrrole, and thiophene or a derivative thereof, and

wherein the second conductive layer having a light-transmitting property comprises a material selected from a group consisting of indium oxide, indium tin oxide, an indium oxide-zinc oxide alloy, zinc oxide, zinc oxide to which gallium is added, graphene, polyaniline or a derivative thereof, polypyrrole or a derivative thereof, polythiophene (PEDOT) or a derivative thereof, and a copolymer of two or more of aniline, pyrrole, and thiophene or a derivative thereof.

13. The light-emitting device according to claim 10,

wherein the first light-emitting element further comprises a third conductive layer having a light-transmitting property between the first electrode having a reflective property and the first light-emitting layer, and

wherein the third conductive layer having a light-transmitting property has a different thickness from the first conductive layer having a light-transmitting property and the second conductive layer having a light-transmitting property.

14. The light-emitting device according to claim 13, wherein the third conductive layer having a light-transmitting property comprises a material selected from a group consisting of indium oxide, indium tin oxide, an indium oxide-zinc oxide alloy, zinc oxide, zinc oxide to which gallium is added, graphene, polyaniline or a derivative thereof, polypyrrole or a derivative thereof, polythiophene (PEDOT) or a derivative thereof, and a copolymer of two or more of aniline, pyrrole, and thiophene or a derivative thereof.

15. The light-emitting device according to claim 10 further comprising a charge generation layer between the first light-emitting layer and the second light-emitting layer.

16. The light-emitting device according to claim 10 further comprising an electrode having a light-transmitting property over the second light-emitting layer.

17. The light-emitting device according to claim 10,

wherein the first optical path length is an optical path length between a surface of the first electrode having a reflective property and a lower surface of the first light-emitting layer or more and an optical path length between the surface of the first electrode having a reflective property and an upper surface of the first light-emitting layer or less,

wherein the second optical path length is an optical path length between a surface of the second electrode having a reflective property and a lower surface of the second light-emitting layer or more and an optical path length between the surface of the second electrode having a reflective property and an upper surface of the second light-emitting layer or less, and

wherein the third optical path length is an optical path length between a surface of the third electrode having a reflective property and a lower surface of the third light-emitting layer or more and an optical path length between the surface of the third electrode having a reflective property and an upper surface of the third light-emitting layer or less.

18. The light-emitting device according to claim 10, wherein the light-emitting device is a display device.

20. The light-emitting device according to claim 10, wherein the visible light range is 380 nm to 680 nm.