Light-emitting device having an electrode with depressions

Patent metadata

Field	Value
Publication number	US-9583739-B2
Application number	US-201414252033-A
Country	US
Kind code	B2
Filing date	Apr 14, 2014
Priority date	Apr 15, 2013
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

In a light-emitting device where reflective electrodes are regularly arranged, occurrence of interference fringes due to reflection of light reflected by the reflective electrode is inhibited. A surface of the reflective electrode of a light-emitting element is provided with a plurality of depressions. The shapes of the plurality of depressions are different from each other and do not have rotational symmetry. Irregularity of the surface shape of the reflective electrode is increased, which inhibits interference of light reflected by the reflective electrode. To form the plurality of depressions in the surface of the reflective electrode, for example, a surface of an insulating layer that is a base of the reflective electrode is made uneven. Reflecting the surface shape of the insulating layer, the reflective electrode has an uneven surface.

First claim

What is claimed is:

1. A light-emitting device comprising:
an insulating layer;
a first electrode over the insulating layer and overlapping with the insulating layer;
a light-emitting layer over the first electrode; and
a second electrode overlapping the first electrode with the light-emitting layer between the first electrode and the second electrode,
wherein the light-emitting layer and the second electrode each overlap a region of the first electrode, a surface of the region being provided with a plurality of depressions formed in response to variations in thickness of the insulating layer, independently of a topography underneath the insulating layer, and
wherein planar shapes of the plurality of depressions are different from each other and do not have rotational symmetry.

2. The light-emitting device according to claim 1 ,
wherein a depth of the depressions is greater than or equal to 0.2 μm and less than or equal to 1.5 μm.

3. The light-emitting device according to claim 1 ,
wherein a tilt angle of the depressions is greater than or equal to 2° and less than or equal to 15°.

4. The light-emitting device according to claim 1 ,
wherein a diameter of a circumcircle of the planar shape of the depressions is greater than or equal to 5 μm and less than or equal to 30 μm.

5. A light-emitting device comprising:
an insulating layer; and
a light-emitting element over the insulating layer,
wherein the light-emitting element comprises:
a first conductive layer over a portion of the insulating layer and overlapping with the portion of the insulating layer;
a light-emitting layer over the first conductive layer; and
a second conductive layer overlapping the first conductive layer with the light-emitting layer between the first conductive layer and the second conductive layer,

wherein a bottom surface of the portion of the insulating layer is flat,
wherein a top surface of the portion of the insulating layer is provided with a plurality of depressions, the top surface facing the bottom surface, and
wherein planar shapes of the plurality of depressions are different from each other and do not have rotational symmetry.

6. The light-emitting device according to claim 5 ,
wherein a depth of the depressions is greater than or equal to 0.2 μm and less than or equal to 1.5 μm.

7. The light-emitting device according to claim 5 ,
wherein a tilt angle of the depressions is greater than or equal to 2° and less than or equal to 15°.

8. The light-emitting device according to claim 5 ,
wherein a diameter of a circumcircle of the planar shape of the depressions is greater than 10 um and less than 30 μm.

9. The light-emitting device according to claim 5 ,
wherein the insulating layer includes a region where one or more kinds of regions having common distribution of the plurality of depressions are arranged in array.

10. The light-emitting device according to claim 5 ,
wherein the light-emitting device comprises a pixel portion in which the light-emitting element is one of light-emitting elements having a same structure arranged in an array.

11. A light-emitting device comprising:
an insulating layer;
a first electrode over a portion of the insulating layer and overlapping with the portion of the insulating layer;
a light-emitting layer over the first electrode; and
a second electrode overlapping the first electrode with the light-emitting layer between the first electrode and the second electrode,
wherein a bottom surface of the portion of the insulating layer is flat,
wherein a top surface of the portion of the insulating layer is provided with a plurality of depressions, the top surface facing the bottom surface, and
wherein planar shapes of the plurality of depressions are different from each other and do not have rotational symmetry.

12. The light-emitting device according to claim 11 ,
wherein a depth of the depressions is greater than or equal to 0.2 μm and less than or equal to 1.5 μm.

13. The light-emitting device according to claim 11 ,
wherein a tilt angle of the depressions is greater than or equal to 2° and less than or equal to 15°.

14. The light-emitting device according to claim 11 ,
wherein a diameter of a circumcircle of the planar shape of the depressions is greater than or equal to 5 μm and less than or equal to 30 μm.

15. The light-emitting device according to claim 11 ,
wherein the insulating layer includes a region where one or more kinds of regions having common distribution of the plurality of depressions are arranged in array.

16. A light-emitting device comprising:
pixel circuits in a pixel portion;
a first insulating layer;
a first electrode and a second electrode, each over the first insulating layer and overlapping with the first insulating layer, and comprised in a first one and a second one of the pixel circuits, respectively;
a second insulating layer over the first insulating layer, between the first electrode and the second electrode, and covering a side portion of the first electrode and a side portion of the second electrode;
a light-emitting layer over the second insulating layer, the first electrode, and the second electrode, and continuously formed from the first electrode to the second electrode; and
a third electrode overlapping the first electrode and the second electrode, with the light-emitting layer between the third electrode and each of the first electrode and the second electrode,
wherein the light-emitting layer and the third electrode each overlap a region of the first electrode, a surface of the region being provided with a plurality of depressions formed in response to variations in thickness of the first insulating layer, independently of a topography underneath the first insulating layer.

17. The light-emitting device according to claim 16 ,
wherein a tilt angle of the depressions is greater than or equal to 2° and less than or equal to 15°.

18. The light-emitting device according to claim 16 ,
wherein a diameter of a circumcircle of planar shaped defined by the depressions is greater than or equal to 5 μm and less than or equal to 30 μm.

19. A light-emitting device comprising:
pixel circuits in a pixel portion;
a first insulating layer;
a second insulating layer over the first insulating layer;
a light-emitting layer over the first insulating layer;
a third conductive layer over the light-emitting layer; and
a first light-emitting element and a second light-emitting element over the first insulating layer,
wherein the first light-emitting element comprises:
a first conductive layer over a first portion of the first insulating layer and overlapping with the first portion of the first insulating layer;
the light-emitting layer over the first conductive layer and the overlapping with the first portion of the first insulating layer; and
the third conductive layer overlapping the first conductive layer with the light-emitting layer between the first conductive layer and the third conductive layer, wherein the second light-emitting element comprises:
a second conductive layer over a second portion of the first insulating layer and overlapping with the second portion of the first insulating layer;
the light-emitting layer over the second conductive layer and overlapping with the second portion of the first insulating layer; and
the third conductive layer overlapping the first conductive layer with the light-emitting layer between the second conductive layer and the third conductive layer,

wherein the second insula

Assignees

• Semiconductor Energy Lab

Inventors

• Hirakata Yoshiharu
• Jikumaru Mika
• Kubota Yusuke
• Kubota Daisuke
• Ishitani Tetsuji
• Shishido Hideaki

Classifications

• H10K59/123

  Connection of the pixel electrodes to the thin film transistors [TFT] · CPC title

• H10K59/1213

  the pixel elements being TFTs · CPC title

• H10K59/8052

  Cathodes · CPC title

• H10K59/878

  comprising reflective means · CPC title

• H10K59/80518

  Reflective anodes, e.g. ITO combined with thick metallic layers · CPC title