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-2016190518-A1
Application number	US-201514984857-A
Country	US
Kind code	A1
Filing date	Dec 30, 2015
Priority date	Dec 31, 2014
Publication date	Jun 30, 2016
Grant date	—

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 light emitting device, comprising:
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, 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 1 , wherein the second electrode is silver.

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

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

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

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

9 . 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.

10 . 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.

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

12 . The light emitting device of claim 11 , wherein the capping layer is a dielectric layer and the refractive index of the capping layer is between 1.4 and 1.6.

13 . The light emitting device of claim 12 , wherein a thickness of the capping layer is greater than or equal to 650 nm.

14 . The light emitting device of claim 13 , wherein the capping layer is silicon dioxide, barium fluoride, calcium fluoride, aluminum oxide, potassium bromide, polymethyl methacrylate, polyacrylate, or polycarbonate.

15 . The light emitting device of claim 3 , 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 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.

20 . 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.

Assignees

• Konica Minolta Lab Usa Inc

Inventors

• Wang Leiming

Classifications

• H10K50/828

  Transparent cathodes, e.g. comprising thin metal layers · CPC title

• H10K50/854

  comprising scattering means · CPC title

• H10K50/11 Primary

  characterised by the electroluminescent [EL] layers · CPC title

• H01L51/5206

  Electricity · mapped topic

• H01L51/5056

  Electricity · mapped topic