Light-emitting device

• US 7,449,724 B2
• Filed: 09/08/2004
• Issued: 11/11/2008
• Est. Priority Date: 09/12/2003
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Nomura, Ryoji, Shimomura, Akihisa, Yamazaki, Shunpei
• Primary Examiner(s): SEFER, AHMED N
• Application Number:
  US10/935,273
• Publication Number:
  US 20050056856A1
• Time in Patent Office: 1,525 Days
• Field of Search: 257 98- 99, 372 87- 88
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01S 5/02212 Can-type, e.g. TO-CAN housings with emission along or parallel to symmetry axis
• CPC Class Codes: H01S 5/02234 Resin-filled housings; the housings being made of resin
• CPC Class Codes: H01S 5/0267 Integrated focusing lens H01S5/18388 takes precedence
• CPC Class Codes: H01S 5/04253 having specific optical properties, e.g. transparent electrodes
• CPC Class Codes: H01S 5/04256 characterised by the configuration
• CPC Class Codes: H01S 5/1039 Details on the cavity length
• CPC Class Codes: H01S 5/14 External cavity lasers H01S5/18 takes precedence; mode locking H01S5/065
• CPC Class Codes: H01S 5/18388 Lenses
• CPC Class Codes: H01S 5/36 comprising organic materials
• CPC Class Codes: H01S 5/423 having a vertical cavity

Abstract

A light-emitting device is disclosed as typified by a laser oscillator formed by an electroluminescent material with improved oscillation efficiency of laser light and even reduced power consumption. The disclosed light-emitting device comprises a light-emitting element including a first electrode having a concave portion, an electroluminescent layer serving as a laser medium formed over the first electrode so as to be overlapped with the concave portion, and a second electrode formed over the electroluminescent layer so as to be overlapped with the concave portion, wherein light generated in the electroluminescent layer is resonated between the first electrode and the second electrode and emitted as laser light from the second electrode, an optical axis of the laser light intersects with the second electrode, the first electrode has a curved surface at the concave portion, and a center of curvature of the curved surface is located at the side of the second electrode above the first electrode.

Claims

1. A light-emitting device comprising:

a first electrode having a concave portion;

an electroluminescent layer having a plane surface formed over the first electrode having a concave portion; and

a second electrode formed over the plane surface so as to be overlapped with the concave portion,

wherein the first electrode has a curved surface at the concave portion,

wherein a focal distance f of a curvature of the concave portion and a distance L between a bottom of the curved surface of the first electrode and the plane surface of the electroluminescent layer satisfies a relationship expressed by formula (1);

f≧

L/2  

 

(1),

wherein the second electrode has a plane surface, and

wherein light generated in the electroluminescent layer is resonated between the first electrode and the second electrode and emitted as laser light through the second electrode.

2. A light-emitting device according to claim 1, wherein the light emitting device is incorporated into one of a laser pointer, projector, or a liquid crystal display device.

3. A light-emitting device comprising:

a first electrode having a concave portion;

an electroluminescent layer having a plane surface formed over the first electrode having a concave portion; and

a second electrode formed over the plane surface so as to be overlapped with the concave portion,

wherein the first electrode has a curved surface at the concave portion,

wherein a focal distance f of a curvature of the concave portion and a distance L between a bottom of the curved surface of the first electrode and the plane surface of the electroluminescent layer satisfies a relationship expressed by formula (1);

f≧

L/2  

 

(1),

wherein the electroluminescent layer includes at least a light-emitting layer and a hole injecting layer formed between the first electrode and the light-emitting layer,

wherein the second electrode has a plane surface, and

wherein light generated in the electroluminescent layer is resonated between the first electrode and the second electrode and emitted as laser light through the second electrode.

4. A light-emitting device according to claim 3, wherein the hole injecting layer comprises a high molecular organic compound.

5. A light-emitting device according to claim 4, wherein the high molecular organic compound is PEDOT.

6. A light-emitting device according to claim 4, wherein the high molecular organic compound is formed by spin coating.

7. A light-emitting device according to claim 3, wherein the light emitting device is incorporated into one of a laser pointer, projector, or a liquid crystal display device.