LIGHT EMITTING DEVICE

• US 20110108864A1
• Filed: 01/19/2011
• Published: 05/12/2011
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: IKEDA, Hisao, SEO, Satoshi, SAKATA, Junichiro, KUMAKI, Daisuke
• Granted Patent: US 8,188,491 B2
• Time in Patent Office: Days
• US Class Current: 257/89
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/171 Electron injection layers
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/131 Interconnections, e.g. wiring lines or terminals
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/631 Amine compounds having at least two aryl rest on at least one amine-nitrogen atom, e.g. triphenylamine
• CPC Class Codes: H10K 85/657 Polycyclic condensed heteroaromatic hydrocarbons
• CPC Class Codes: Y02E 10/549 Organic PV cells

Abstract

Light-emitting elements have a problem that their light-extraction efficiency is low due to scattered light or reflected light inside the light-emitting elements. The light-extraction efficiency of the light-emitting elements needs to be enhanced by a new method. According to the present invention, a light-emitting element includes a first layer generating holes, a second layer including a light-emitting layer for each emission color and a third layer generating electrons between an anode and a cathode, and the thickness of the first layer is different depending on each layer including the light-emitting layer for each emission color. A layer in which an organic compound and a metal oxide are mixed is used as the first layer, and thus, the driving voltage is not increased even when the thickness is increased, which is preferable.

Claims

1. A light-emitting device having at least first and second light-emitting elements exhibiting different emission colors, each of the first and second light-emitting elements comprising:

a first electrode that has a non-light-transmitting property;

a first layer serving as a layer generating holes over the first electrode;

a second layer serving as a layer including a light-emitting layer over the first layer;

a third layer serving as a layer generating electrons over the second layer; and

a second electrode that has a light transmitting property over the third layer,

wherein a thickness of the first layer of the first light-emitting element is different from that of the second light-emitting element, and

wherein the first layer has an absorption peak around 500 nm.

2. The light-emitting device according to claim 1, wherein the first electrode is electrically connected to a transistor provided at interconnection portion formed by a signal line and a scanning line.

3. The light-emitting device according to claim 1, further comprising a plurality of types of color filters having different optical characteristics over the second electrode.

4. The light-emitting device according to claim 1, wherein the second electrode comprises indium tin oxide including silicon oxide.

5. The light-emitting device according to claim 1,

wherein an optical distance between the light-emitting layer and the first electrode is (2 m−

1)/4 -fold of an emission wavelength, and

wherein m is a positive integer.

6. The light-emitting device according to claim 1, wherein the light-emitting device is incorporated in an electronic device selected from the group consisting of a television set, cameras, a portable information terminal, a monitor for a computer, a computer, a sound reproducing device, and an image reproducing device.

7. The light-emitting device according to claim 1,

wherein the first light-emitting element generates blue light,

wherein the second light-emitting element generates red light, and

wherein the thickness of the first light-emitting element is thicker than that of the second light-emitting element.

8. The light-emitting device according to claim 1, wherein a thickness of the third layer of the first light-emitting element is different from that of the second light-emitting element.

9. A light-emitting device having at least first and second light-emitting elements exhibiting different emission colors, each of the first and second light-emitting elements comprising:

a first electrode that has a non-light-transmitting property;

a first layer serving as a layer generating holes over the first electrode;

a second layer serving as a layer including a light-emitting layer over the first layer;

a third layer serving as a layer generating electrons over the second layer;

a fourth layer serving as a layer generating holes over the third layer; and

a second electrode that has a light transmitting property over the fourth layer,

wherein a thickness of the first layer of the first light-emitting element is different from that of the second light-emitting element, and

wherein the first layer has an absorption peak around 500 nm.

10. The light-emitting device according to claim 9, wherein the first electrode is electrically connected to a transistor provided at interconnection portion formed by a signal line and a scanning line.

11. The light-emitting device according to claim 9, further comprising a plurality of types of color filters having different optical characteristics over the second electrode.

12. The light-emitting device according to claim 9, wherein the second electrode comprises indium tin oxide including silicon oxide.

13. The light-emitting device according to claim 9,

wherein an optical distance between the light-emitting layer and the first electrode is (2 m−

1)/4 -fold of an emission wavelength, and

wherein m is a positive integer.

14. The light-emitting device according to claim 9, wherein the light-emitting device is incorporated in an electronic device selected from the group consisting of a television set, cameras, a portable information terminal, a monitor for a computer, a computer, a sound reproducing device, and an image reproducing device.

15. The light-emitting device according to claim 9,

wherein the first light-emitting element generates blue light,

wherein the second light-emitting element generates red light, and

wherein the thickness of the first light-emitting element is thicker than that of the second light-emitting element.

16. The light-emitting device according to claim 9, wherein a thickness of the third layer of the first light-emitting element is different from that of the second light-emitting element.

17. A light-emitting device having at least first and second light-emitting elements exhibiting different emission colors, each of the first and second light-emitting elements comprising:

a first electrode that has a non-light-transmitting property;

a first layer serving as a layer generating holes over the first electrode;

a second layer serving as a layer including a light-emitting layer over the first layer;

a third layer serving as a layer generating electrons over the second layer; and

a second electrode that has a light transmitting property over the third layer,

wherein the second electrode comprises a semi-transparent metal material,

wherein a thickness of the first layer of the first light-emitting element is different from that of the second light-emitting element, and

wherein the first layer has an absorption peak around 500 nm.

18. The light-emitting device according to claim 17, wherein the first electrode is electrically connected to a transistor provided at interconnection portion formed by a signal line and a scanning line.

19. The light-emitting device according to claim 17, further comprising a plurality of types of color filters having different optical characteristics over the second electrode.

20. The light-emitting device according to claim 17, wherein the second electrode comprises indium tin oxide including silicon oxide.

21. The light-emitting device according to claim 17, wherein an optical distance between the light-emitting layer and the first electrode is (2 m−

1)/4 -fold of an emission wavelength, and wherein m is a positive integer.

22. The light-emitting device according to claim 17, wherein the light-emitting device is incorporated in an electronic device selected from the group consisting of a television set, cameras, a portable information terminal, a monitor for a computer, a computer, a sound reproducing device, and an image reproducing device.

23. The light-emitting device according to claim 17,

wherein the first light-emitting element generates blue light,

wherein the second light-emitting element generates red light, and

wherein the thickness of the first light-emitting element is thicker than that of the second light-emitting element.

24. The light-emitting device according to claim 17, wherein a thickness of the third layer of the first light-emitting element is different from that of the second light-emitting element.

25. A light-emitting device having at least first and second light-emitting elements exhibiting different emission colors, each of the first and second light-emitting elements comprising:

a first electrode that has a non-light-transmitting property;

a first layer serving as a layer generating holes over the first electrode;

a second layer serving as a layer including a light-emitting layer over the first layer;

a third layer serving as a layer generating electrons over the second layer;

a fourth layer serving as a layer generating holes over the third layer; and

a second electrode that has a light transmitting property over the fourth layer,

wherein the second electrode comprises a semi-transparent metal material,

wherein a thickness of the first layer of the first light-emitting element is different from that of the second light-emitting element, and

wherein the first layer has an absorption peak around 500 nm.

26. The light-emitting device according to claim 25, wherein the first electrode is electrically connected to a transistor provided at interconnection portion formed by a signal line and a scanning line.

27. The light-emitting device according to claim 25, further comprising a plurality of types of color filters having different optical characteristics over the second electrode.

28. The light-emitting device according to claim 25, wherein the second electrode comprises indium tin oxide including silicon oxide.

29. The light-emitting device according to claim 25,

wherein an optical distance between the light-emitting layer and the first electrode is (2 m−

1)/4 -fold of an emission wavelength, and

wherein m is a positive integer.

30. The light-emitting device according to claim 25, wherein the light-emitting device is incorporated in an electronic device selected from the group consisting of a television set, cameras, a portable information terminal, a monitor for a computer, a computer, a sound reproducing device, and an image reproducing device.

31. The light-emitting device according to claim 25,

wherein the first light-emitting element generates blue light,

wherein the second light-emitting element generates red light, and

wherein the thickness of the first light-emitting element is thicker than that of the second light-emitting element.

32. The light-emitting device according to claim 25, wherein a thickness of the third layer of the first light-emitting element is different from that of the second light-emitting element.