Nanoparticle material and light-emitting device

Patent metadata

Field	Value
Publication number	US-9595625-B2
Application number	US-201615096696-A
Country	US
Kind code	B2
Filing date	Apr 12, 2016
Priority date	Oct 17, 2013
Publication date	Mar 14, 2017
Grant date	Mar 14, 2017

Abstract

Quantum dots (nanoparticle material) each having a core-shell structure including a core part and a shell part that protects the core part. The shell part of the quantum dot has a thickness T of 3 to 5 ML based on the constituent molecule of the shell part. A light-emitting device includes the quantum dots.

First claim

The invention claimed is:

1. A light-emitting device comprising:
a hole transport layer;
an electron transport layer;
a first light-emitting layer interposed between the hole transport layer and the electron transport layer, the first light-emitting layer comprising first quantum dots, the first light-emitting layer being constructed to emit light when an electric current is injected into the first light-emitting layer, wherein the first quantum dots are a nanoparticle material comprising a first core part and a first shell part coating the first core part, the first shell part having a thickness of 3 to 5 monolayers of a constituent molecule of the first shell part; and
a second light-emitting layer, the second light-emitting layer comprising second quantum dots, the second light-emitting layer being constructed to emit light when the electric current is injected into the second light-emitting layer, wherein the second quantum dots are a nanoparticle material comprising a second core part and a second shell part coating the second core part, the second shell part having a thickness of less than 3 monolayers based on a constituent molecule of the second shell part,
the first light-emitting layer being disposed proximal to the electron transport layer relative to the second light-emitting layer, and the second light-emitting layer being disposed proximal to the hole transport layer relative to the first light-emitting layer, and
the first shell part has a greater thickness than the second shell part.

2. The light-emitting device according to claim 1 , wherein the first shell part has a first energy level of a valence band on the basis of a vacuum level, and the first core part has a second energy level of a valence band on the basis of the vacuum level, the first energy level being lower than the second energy level.

3. The light-emitting device according to claim 1 , wherein the first shell part has an energy level of a valence band on the basis of a vacuum level that is lower than a HOMO level of the electron transport layer.

4. The light-emitting device according to claim 1 , wherein the first light-emitting layer has a thickness of 0.5 to 2 monolayers based on a particle size of the first quantum dots.

5. The light-emitting device according to claim 2 , wherein the first light-emitting layer has a thickness of 0.5 to 2 monolayers based on a particle size of the first quantum dots.

6. The light-emitting device according to claim 3 , wherein the first light-emitting layer has a thickness of 0.5 to 2 monolayers based on a particle size of the first quantum dots.

Assignees

• Murata Manufacturing Co

Inventors

• Murayama Koji
• Miyata Haruya

Classifications

• C09K11/565 Primary

  with zinc cadmium · CPC title

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title

• C09K11/883

  with zinc or cadmium · CPC title

• B82Y20/00

  Nanooptics, e.g. quantum optics or photonic crystals · CPC title

• C01P2004/80

  Particles consisting of a mixture of two or more inorganic phases · CPC title