# US 7,745,989 B2 · Light emitting element, light emitting device, and electronic apparatus

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- Number: US 7,745,989 B2
- Document ID: US7745989B2
- Status: Granted
- Kind: B2
- Application number: 11/473,332
- Filed: 2006-06-23
- Published: 2007-01-18
- Granted: 2010-06-29
- Earliest claimed: 2005-06-30
- Assignees: Semiconductor Energy Laboratory Co., Ltd.
- Inventors: Shunpei Yamazaki; Junichiro Sakata; Ryoji Nomura
- Web page: https://patentgrep.com/patent/US7745989B2

## CPC

- H10K 50/14: Carrier transporting layers
- Y10S 428/917: Electroluminescent
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

It is an object of the present invention to provide a light emitting element with a low driving voltage. In a light emitting element, a first electrode; and a first composite layer, a second composite layer, a light emitting layer, an electron transporting layer, an electron injecting layer, and a second electrode, which are stacked over the first electrode, are included. The first composite layer and the second composite layer each include metal oxide and an organic compound. A concentration of metal oxide in the first composite layer is higher than a concentration of metal oxide in the second composite layer, whereby a light emitting element with a low driving voltage can be obtained. Further, the composite layer is not limited to a two-layer structure. A multi-layer structure can be employed. However, a concentration of metal oxide in the composite layer is gradually higher from the light emitting layer to first electrode side.

## Claims

### Claim 1

A light emitting element comprising:
a first electrode;
a composite layer being in contact with the first electrode;
a light emitting layer over the composite layer;
an electron transporting layer over the light emitting layer; and
a second electrode over the electron transporting layer,
wherein the composite layer includes molybdenum oxide and an organic compound,
wherein molybdenum oxide in the composite layer has a concentration gradient from the first electrode side to light emitting layer side, and
wherein a concentration of molybdenum oxide contained in the composite layer is gradually lowered from the first electrode side toward the light emitting layer side.

### Claim 2 (depends on 1)

A light emitting element according to claim 1,
wherein the organic compound has a hole transporting property.

### Claim 3 (depends on 1)

A light emitting element according to claim 1,
wherein the organic compound has an arylamine skeleton or a carbazole skeleton.

### Claim 4 (depends on 1)

A light emitting device comprising a light emitting element according to claim 1.

### Claim 5 (depends on 4)

An electronic apparatus comprising a light emitting device according to claim 4.

### Claim 6 (depends on 1)

A light emitting element according to claim 1,
wherein a concentration of molybdenum oxide in the composite layer has the lowest concentration at a surface in contact with the light emitting layer.

### Claim 7 (depends on 6)

A light emitting element according to claim 6,
wherein the organic compound has a hole transporting property.

### Claim 8 (depends on 6)

A light emitting element according to claim 6,
wherein the organic compound has an arylamine skeleton or a carbazole skeleton.

### Claim 9 (depends on 6)

A light emitting device comprising a light emitting element according to claim 6.

### Claim 10 (depends on 9)

An electronic apparatus comprising a light emitting device according to claim 9.

### Claim 11 (depends on 1)

A light emitting element according to claim 1,
wherein a concentration of molybdenum oxide in the composite layer is 0 wt % or more and 3 wt % or less at a surface in contact with the light emitting layer.

### Claim 12 (depends on 11)

A light emitting element according to claim 11,
wherein the organic compound has a hole transporting property.

### Claim 13 (depends on 11)

A light emitting element according to claim 11,
wherein the organic compound has an arylamine skeleton or a carbazole skeleton.

### Claim 14 (depends on 11)

A light emitting device comprising a light emitting element according to claim 11.

### Claim 15 (depends on 14)

An electronic apparatus comprising a light emitting device according to claim 14.

### Claim 16 (depends on 1)

A light emitting element according to claim 1, wherein an unevenness process is implemented on a surface of the first electrode.

### Claim 17 (depends on 1)

A light emitting element according to claim 1, wherein a high concentration region of molybdenum oxide is at least the same or at most eight times as a low concentration region.