Light-emitting devices using thin film electrode with refractive index optimized capping layer for reduction of plasmonic energy loss

Patent metadata

Field	Value
Publication number	US-9722208-B2
Application number	US-201514984857-A
Country	US
Kind code	B2
Filing date	Dec 30, 2015
Priority date	Dec 31, 2014
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

A light emitting device includes a substrate, a first electrode disposed on the substrate, a light emission layer (EML) disposed on the first electrode, a second electrode disposed on the EML, and a capping layer disposed on the second electrode. A thickness of the second electrode is not more than 50 nm, a refractive index of the capping layer is less than a refractive index of the EML, and the EML and the second electrode are separated by a distance not more than 100 nm.

First claim

What is claimed is:

1. A bottom emitting light emitting device, comprising:
a substrate configured to emit light;
a first electrode disposed on the substrate;
a light emission layer (EML) disposed on the first electrode;
a second electrode disposed on the EML; and
a capping layer disposed on the second electrode,
wherein a thickness of the second electrode is not more than 50 nm,
wherein a refractive index of the capping layer is less than a refractive index of the EML, and
wherein the EML and the second electrode are separated by a distance not more than 100 nm.

2. The light emitting device of claim 1 , further comprising:
a hole transport layer disposed between the first electrode and the EML; and
an electron transport layer disposed between the EML and the second electrode, wherein a thickness of the electron transport layer is less than 100 nm.

3. The light emitting device of claim 2 , wherein the refractive index of the capping layer is less than a refractive index of the electron transport layer.

4. The light emitting device of claim 3 , wherein the thickness of the second electrode is between 10 nm and 30 nm.

5. The light emitting device of claim 4 , wherein the capping layer is a dielectric layer and the refractive index of the capping layer is between 1.4 and 1.6.

6. The light emitting device of claim 5 , wherein a thickness of the capping layer is greater than or equal to 650 nm.

7. The light emitting device of claim 6 , wherein the capping layer is silicon dioxide, barium fluoride, calcium fluoride, aluminum oxide, potassium bromide, polymethyl methacrylate, polyacrylate, or polycarbonate.

8. The light emitting device of claim 2 , wherein the thickness of the second electrode is between 10 nm and 30 nm.

9. The light emitting device of claim 8 , wherein the capping layer is a dielectric layer and the refractive index of the capping layer is between 1.4 and 1.6.

10. The light emitting device of claim 9 , wherein a thickness of the capping layer is greater than or equal to 650 nm.

11. The light emitting device of claim 10 , wherein the capping layer is silicon dioxide, barium fluoride, calcium fluoride, aluminum oxide, potassium bromide, polymethyl methacrylate, polyacrylate, or polycarbonate.

12. The light emitting device of claim 2 , further comprising:
an internal extraction structure disposed between the substrate and the first electrode, wherein the internal extraction structure comprises high refractive index particles and extracts light from a waveguide mode.

13. The light emitting device of claim 2 , further comprising:
a microlens array formed on a surface of the substrate opposite the first electrode, wherein the microlens array extracts light from a substrate mode.

14. The light emitting device of claim 1 , wherein the second electrode is silver.

15. The light emitting device of claim 1 , wherein the thickness of the second electrode is between 10 nm and 30 nm.

16. The light emitting device of claim 15 , wherein the capping layer is a dielectric layer and the refractive index of the capping layer is between 1.4 and 1.6.

17. The light emitting device of claim 16 , wherein a thickness of the capping layer is greater than or equal to 650 nm.

18. The light emitting device of claim 17 , wherein the capping layer is silicon dioxide, barium fluoride, calcium fluoride, aluminum oxide, potassium bromide, polymethyl methacrylate, polyacrylate, or polycarbonate.

19. The light emitting device of claim 1 , further comprising:
an internal extraction structure disposed between the substrate and the first electrode, wherein the internal extraction structure comprises high refractive index particles and extracts light from a waveguide mode.

20. The light emitting device of claim 1 , further comprising:
a microlens array formed on a surface of the substrate opposite the first electrode, wherein the microlens array extracts light from a substrate mode.

21. A light emitting device, comprising:
a substrate through which a majority of light generated by a light emission layer (EML) is radiated;
a first electrode disposed on the substrate;
the EML, disposed on the first electrode, that generates the light;
a second electrode disposed on the EML; and
a capping layer disposed on the second electrode,
wherein a thickness of the second electrode is not more than 50 nm,
wherein a refractive index of the capping layer is less than a refractive index of the EML, and
wherein the EML and the second electrode are separated by a distance not more than 100 nm.

22. A light emitting device, comprising:
a substrate;
a first electrode, disposed on the substrate, configured to transmit light generated by a light emission layer (EML) to the substrate;
the EML disposed on the first electrode;
a second electrode disposed on the EML; and
a capping layer disposed on the second electrode,
wherein a thickness of the second electrode is not more than 50 nm,
wherein a refractive index of the capping layer is less than a refractive index of the EML, and
wherein the EML and the second electrode are separated by a distance not more than 100 nm.

Assignees

• Konica Minolta Laboratory Usa Inc

Inventors

• Wang Leiming

Classifications

• H01L51/5268 Primary

  Electricity · mapped topic

• H01L2251/558

  Electricity · mapped topic

• H01L51/5275

  Electricity · mapped topic

• H01L51/5004

  Electricity · mapped topic

• H01L51/5234

  Electricity · mapped topic