Light emitting device

• US 20070131948A1
• Filed: 09/22/2005
• Published: 06/14/2007
• Est. Priority Date: 09/24/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi, Kumaki, Daisuke, Ikeda, Hisao, Sakata, Junichiro
• Granted Patent: US 7,601,988 B2
• Time in Patent Office: Days
• US Class Current: 257/87
• 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 element comprising:

a first electrode and a second electrode; and

a first layer, a second layer and a third layer which are formed between the first electrode and the second electrode,

wherein the first layer serves as a layer generating holes, the second layer serves as a layer including a light-emitting layer, and the third layer serves as a layer generating electrons, and

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

3. The light-emitting device according to any one of claims 1 and 2, wherein the thickness of the first layer of the first light-emitting element is different from that of the second light-emitting element so that so that light-extraction efficiency of light emitted from the light-emitting layer and reflected light, which has been emitted from the light-emitting layer and is reflected on the first electrode, can be increased.

8. The light-emitting device according to any one of claims 1, 2, 6 and 7, wherein the second electrode comprises indium tin oxide including silicon oxide.

2. 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 element comprising:

a first electrode and a second electrode; and

a first layer, a second layer and a third layer which are formed between the first electrode and the second electrode,

wherein the first layer serves as a layer generating holes, the second layer serves as a layer including a light-emitting layer, and the third layer serves as a layer generating electrons,

wherein a first layer is a layer in which an organic compound and a metal oxide are mixed, and

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

4. The light-emitting device according to claim 2, wherein the metal oxide is selected from the group consisting of molybdenum oxide, vanadium oxide and rhenium oxide.

5. The light-emitting device according to claim 2, wherein the organic compound is selected from the group consisting of 4,4′

-bis[N-(1-naphthyl)-N-phenylamino]biphenyl;

4,4′

-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl;

4,4′

,4″

-tris(N,N-diphenylamino)triphenylamine;

4,4′

,4″

-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine;

4,4′

-bis{N-[4-(N,N-di-m-tolylamino)phenyl]-N-phenylamino}biphenyl;

phthalocyanine;

copper phthalocyanine; and

vanadyl phthalocyanine.

6. 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 and a second electrode; and

a first layer, a second layer, a third layer and a fourth layer which are formed between the first electrode and the second electrode,

wherein the first layer serves as a layer generating holes, the second layer serves as a layer including a light-emitting layer, the third layer serves as a layer generating electrons, and the fourth layer serves as a layer generating holes, and

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

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

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

a first layer, a second layer, a third layer and a fourth layer which are formed between the first electrode and the second electrode,

wherein the first layer serve as a layer generating holes, the second layer serves as a layer including a light-emitting layer, the third layer serves as a layer generating electrons, and the fourth layer serves as a layer generating holes, and

wherein a thickness of the first layer is different depending on each of the emission colors so that light-extraction efficiency of light emitted from the light-emitting layer and reflected light, which has been emitted from the light-emitting layer and is reflected on the first electrode, can be increased.

9. A light-emitting device comprising:

a plurality of transistors provided at interconnection portions formed by signal lines and scanning lines;

a plurality of first electrodes that are connected to the plurality of transistors;

a second electrode provided to be opposed to the plurality of first electrodes;

a plurality of first layers, a plurality of second layers and a plurality of third layers which are formed between the plurality of first electrodes and the second electrode;

wherein the plurality of first layers serve as layers generating holes, and the plurality of second layers serve as layers including any of light-emitting layers emitting first to third light, and the plurality of third layers serves as layers generating electrons, and

wherein thicknesses of the plurality of first layers are different depending on each light-emitting element emitting the first to third light.

10. A light-emitting device comprising:

a plurality of transistors provided at interconnection portions formed by signal lines and scanning lines;

a plurality of first electrodes that are connected to the plurality of transistors;

a second electrode provided to be opposed to the plurality of first electrodes; and

a plurality of first layers, a plurality of second layers and a plurality of third layers which are formed between the plurality of first electrodes and the second electrode,

wherein the plurality of first layers serve as layers generating holes, and the plurality of second layers each serve as a layer including at least one of light-emitting layers emitting first to third light, and the plurality of third layers serves as layers generating electrons, and

wherein the plurality of first layers are each a layer in which an organic compound and a metal oxide are mixed, and

wherein thicknesses of the first layers are different depending on each light-emitting element emitting the first to third light.

11. The light-emitting device according to any one of claims 9 and 10, wherein the metal oxide is molybdenum oxide, vanadium oxide and rhenium oxide.

14. The light-emitting device according to any one of claims 9, 10 and 12, wherein the organic compound is selected from the group consisting of 4,4′

-bis[N-(1-naphthyl)-N-phenylamino]biphenyl;

4,4′

-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl;

4,4′

,4″

-tris(N,N-diphenylamino)triphenylamine;

4,4′

,4″

-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine;

4,4′

-bis {N-[4-(N,N-di-m-tolylamino)phenyl]-N-phenylamino}biphenyl;

phthalocyanine;

copper phthalocyanine; and

vanadyl phthalocyanine.

15. The light-emitting device according to any one of claims 9, 10 and 12, wherein the second electrode comprises indium tin oxide including silicon oxide.

12. A light-emitting device comprising:

a plurality of transistors provided at interconnection portions formed by signal lines and scanning lines;

a plurality of first electrodes that are connected to the plurality of transistors;

a second electrode provided to be opposed to the plurality of first electrodes; and

a plurality of first layers, a plurality of second layers, a plurality of third layers and a plurality of fourth layers which are formed between the plurality of first electrodes and the second electrode,

wherein the plurality of first layers serve as layers generating holes, and the plurality of second layers serve as a layer including at least one of light-emitting layers emitting first to third light, the plurality of third layers serve as layers generating electrons, the plurality of fourth layers serve layers generating holes, and

wherein thicknesses of the plurality of first layers are different depending on each light-emitting element emitting the first to third light.

13. The light-emitting device according to claim 12, wherein thicknesses of the plurality of first layers are different depending on each light-emitting element emitting the first to third light so that light-extraction efficiency of light emitted from the light-emitting layer and reflected light, which has been emitted from the light-emitting layer and is reflected on the first electrode, can be increased.

16. Alight-emitting device comprising:

a plurality of types of color filters having different optical characteristics;

a first electrode and a second electrode; and

a first layer, a second layer and a third layer formed between the first electrode and the second electrode,

wherein any of the first to third layers has an organic material and a metal oxide, and

wherein a thickness of the layer having the organic material and the metal oxide is different depending on each of the optical characteristics.

20. The light-emitting device according to any one of claims 16 to 19, wherein the plurality of types of color filters are formed on an emission side.

21. The light-emitting device according to any one of claims 16 to 19, wherein the metal oxide is selected from the group consisting of molybdenum oxide, vanadium oxide and rhenium oxide.

22. The light-emitting device according to any one of claims 16 to 19, wherein at least one of the first and second electrodes comprises indium tin oxide including silicon oxide.

17. A light-emitting device comprising:

a plurality of types of color filters having different optical characteristics;

a first electrode and a second electrode; and

a first layer, a second layer and a third layer formed between the first electrode and the second electrode,

wherein the first layer serves as a layer generating holes, and the second layer serves as a layer including a light-emitting layer, and the third layer serves as a layer generating electrons,

wherein the first layer has an organic material and a metal oxide, and

wherein a thickness of the first layer is different depending on each of the optical characteristics.

18. A light-emitting device comprising:

a semiconductor film;

a first electrode and a second electrode formed over the semiconductor film;

a first layer, a second layer and a third layer formed between the first electrode and the second electrode,

a plurality of types of color filters having different optical characteristics, which are formed on the first electrode side,

wherein the first electrode has a light-transmitting property,

wherein the first layer serves as a layer generating holes, and the second layer serves as a layer including a light-emitting layer, and the third layer serves as a layer generating electrons,

wherein the first layer has an organic material and a metal oxide, and

wherein a thickness of the first layer is different depending on each of the optical characteristics.

19. A light-emitting device comprising:

a semiconductor film;

a first electrode and a second electrode formed over the semiconductor film;

a first layer, a second layer and a third layer formed between the first electrode and the second electrode,

a plurality of types of color filters having different optical characteristics, which are each formed on the first electrode side,

wherein the second electrode has a light-transmitting property,

wherein the first layer serves as a layer generating holes, and the second layer serves as a layer including a light-emitting layer, and the third layer serves as a layer generating electrons;

wherein the first layer has an organic material and a metal oxide; and

wherein a thickness of the first layer is different depending on each of the optical characteristics.