Light-emitting device

• US 20050056856A1
• Filed: 09/08/2004
• Published: 03/17/2005
• Est. Priority Date: 09/12/2003
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Nomura, Ryoji, Shimomura, Akihisa, Yamazaki, Shunpei
• Granted Patent: US 7,449,724 B2
• Time in Patent Office: Days
• 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 formed over the first electrode so as to cover the concave portion; and

a second electrode formed over the electroluminescent layer so as to be overlapped with the concave portion,

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

wherein a center of curvature of the curved surface is located at the second electrode side,

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 from 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.

22. A light-emitting device according to claim 1, wherein a distance of the first electrode to the center of curvature is longer than that of the first electrode to the second electrode.

3. A light-emitting device comprising:

a first electrode having a concave portion;

an electroluminescent layer formed over the first electrode so as to cover the concave portion; and

a second electrode formed over the electroluminescent layer so as to be overlapped with the concave portion,

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

wherein a center of curvature of the curved surface is located at the second electrode side,

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 from 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.

23. A light-emitting device according to claim 3, wherein a distance of the first electrode to the center of curvature is longer than that of the first electrode to the second electrode.

8. A light-emitting device comprising:

a first layer having a concave portion;

a second layer formed over the first layer so as to cover the concave portion;

a light-emitting element formed over the second layer so as to be overlapped with the concave portion,

wherein the light-emitting element includes a first electrode formed over the second layer, an electroluminescent layer formed over the first electrode, and a second electrode formed over the electroluminescent layer,

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

wherein a center of curvature of the curved surface is located at the light-emitting element side,

wherein a refraction index of the first layer is lower than that of the second layer, and

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

9. A light-emitting device according to claim 8, wherein the first layer is a glass substrate, a quartz substrate, a plastic substrate, a resin film deposited over the substrate, or an insulating film deposited over the substrate.

10. A light-emitting device according to claim 8, wherein the second layer comprises a material having light-transmitting properties.

11. A light-emitting device according to claim 8, wherein a reflective film is formed over the concave portion of the first layer, and the reflective layer comprises a material containing one or a plurality of metal elements such as Al, Ag, Ti, W, Pt, or Cr.

12. A light-emitting device according to claim 8, wherein the light emitting device is incorporated into one of a laser pointer, projector, or a liquid crystal display device.

24. A light-emitting device according to claim 8, wherein a distance of the first layer to the center of curvature is longer than that of the first layer to the light-emitting element.

13. A light-emitting device comprising:

a first electrode having a concave portion;

an electroluminescent layer formed over the first electrode so as to cover the concave portion;

a second electrode formed over the electroluminescent layer so as to be overlapped with the concave portion;

a first layer having a convex portion formed over the second electrode; and

a second layer formed so as to cover the first layer having the convex portion;

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

wherein the second layer has a curved surface at the convex portion;

wherein a center of curvature of the curved surface of the first electrode is located at the second electrode side,

wherein a center of curvature of the curved surface of the second layer is located at the second electrode side,

wherein a refraction index of the first layer is lower than that of the second layer, and

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

14. A light-emitting device according to claim 13, wherein the light emitting device is incorporated into one of a laser pointer, projector, or a liquid crystal display device.

25. A light-emitting device according to claim 13, wherein a distance of the first electrode to the center of curvature is-longer than that of the first electrode to the second electrode.

26. A light-emitting device according to claim 13, wherein a distance of the second layer to the center of curvature is longer than that of the second layer to the second electrode.

15. A light-emitting device comprising:

a first layer having a concave portion;

a second layer formed over the first layer so as to cover the concave portion;

a light-emitting element formed over the second layer so as to be overlapped with the concave portion;

a third layer having a convex portion formed over the light-emitting element;

a fourth layer formed so as to cover the layer having the convex portion;

wherein the light-emitting element includes a first electrode formed over the second layer, an electroluminescent layer formed over the first electrode, and a second electrode formed over the electroluminescent layer,

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

wherein the fourth layer has a curved surface at the convex portion,

wherein a center of curvature of the curved surface of the first layer is located at the light-emitting element side,

wherein a center of curvature of the curved surface of the fourth layer is located at the light-emitting element side,

wherein a refractive index of the first layer is lower than that of the second layer,

wherein a refractive index of the fourth layer is lower than that of the third layer, and

wherein light generated in the electroluminescent layer is resonated between the first layer and the fourth layer and emitted as laser light from the fourth layer.

16. A light-emitting device according to claim 15, wherein the first layer is a glass substrate, a quartz substrate, a plastic substrate, a resin film deposited over the substrate, or an insulating film deposited over the substrate.

17. A light-emitting device according to claim 15, wherein the second layer comprises a material having light-transmitting properties.

18. A light-emitting device according to claim 15, wherein a reflective film is formed over the concave portion of the first layer, and the reflective layer comprises a material containing one or a plurality of metal elements such as Al, Ag, Ti, W, Pt, or Cr.

19. A light-emitting device according to claim 15, wherein the light emitting device is incorporated into one of a laser pointer, projector, or a liquid crystal display device.

27. A light-emitting device according to claim 15, wherein a distance of the first layer to the center of curvature is longer than that of the first layer to the light-emitting element.

20. A light-emitting device comprising:

a first electrode having a concave portion;

an electroluminescent layer formed over the first electrode so as to cover the concave portion;

a second electrode formed over the electroluminescent layer so as to be overlapped with the concave portion; and

a layer having a convex portion formed over the second electrode,

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

wherein a center of curvature of the curved surface is located at the second electrode side,

wherein the second electrode has a plane surface,

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

wherein directivity of the laser light is improved by refraction of the laser light at the concave portion.

21. A light-emitting device according to claim 20, wherein the light emitting device is incorporated into one of a laser pointer, projector, or a liquid crystal display device.

28. A light-emitting device according to claim 20, wherein a distance of the first electrode to the center of curvature is longer than that of the first electrode to the second electrode.

29. A light-emitting device according to claim 20, wherein a distance of the layer to the center of curvature is longer than that of the layer to the second electrode.