Light-emitting element, display device, and electronic appliance

• US 8,618,574 B2
• Filed: 06/16/2011
• Issued: 12/31/2013
• Est. Priority Date: 08/04/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kumaki, Daisuke, Seo, Satoshi
• Primary Examiner(s): Dickey, Thomas L
• Application Number:
  US13/161,619
• Publication Number:
  US 20110241007A1
• Time in Patent Office: 929 Days
• Field of Search: 257/103, 257/E51.051, 313/504, 313/506
• US Class Current: 257/103
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/15 Hole transporting layers
• CPC Class Codes: H10K 50/155 comprising dopants
• CPC Class Codes: H10K 50/157 between the light-emitting layer and the cathode
• CPC Class Codes: H10K 50/16 Electron transporting layers
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays

Abstract

The present invention provides a light-emitting element having a structure in which the drive voltage is comparatively low and a light-emitting element in which the increase in the drive voltage over time is small. Further, the present invention provides a display device in which the drive voltage and the increase in the drive voltage over time are small and which can resist long-term use. A layer in contact with an electrode in a light-emitting element is a layer containing a P-type semiconductor or a hole-generating layer such as an organic compound layer containing a material having electron-accepting properties. The light-emitting layer is sandwiched between the hole-generating layers, and an electron-generating layer is sandwiched between the light-emitting layer and the hole-generating layer on a cathode side.

Claims

1. An electronic device comprising:

a light-emitting device comprising;

a substrate comprising an organic compound;

an anode over the substrate;

a first layer over the anode, the first layer generating holes;

a light emitting layer comprising a light emitting material over the first layer;

a second layer over the light emitting layer, the second layer generating electrons;

a third layer comprising metal oxide over the second layer, the third layer generating holes; and

a cathode being in contact with the third layer.

2. The electronic device according to claim 1, further comprising a counter substrate over the cathode,

wherein the substrate comprises a material selected from the group consisting of polyimide, acrylic, polyethylene terephthalate, polycarbonate, polyacrylate, and polyethersulfone.

3. The electronic device according to claim 1,

wherein the metal oxide is selected from the group consisting of vanadium oxide, molybdenum oxide, cobalt oxide, and nickel oxide.

4. The electronic device according to claim 1,

wherein the light-emitting device is a display device.

5. The electronic device according to claim 1, further comprising a counter substrate over the cathode,

wherein the substrate is a plastic substrate.

6. The electronic device according to claim 1, further comprising a counter substrate over the cathode.

7. The electronic device according to claim 1, wherein a display portion comprises the light-emitting device.

8. An electronic device comprising:

a light-emitting device comprising;

a substrate comprising an organic compound;

a semiconductor layer over the substrate;

a gate electrode adjacent to the semiconductor layer with an insulating layer interposed between the gate electrode and the semiconductor layer;

an anode over the substrate, the anode electrically connected to the semiconductor layer;

a first layer over the anode, the first layer generating holes;

a light emitting layer comprising a light emitting material over the first layer;

a second layer over the light emitting layer, the second layer generating electrons;

a third layer comprising metal oxide over the second layer, the third layer generating holes; and

a cathode being in contact with the third layer.

9. The electronic device according to claim 8, further comprising a counter substrate over the cathode,

wherein the substrate comprises a material selected from the group consisting of polyimide, acrylic, polyethylene terephthalate, polycarbonate, polyacrylate, and polyethersulfone.

10. The electronic device according to claim 8,

wherein the metal oxide is selected from the group consisting of vanadium oxide, molybdenum oxide, cobalt oxide, and nickel oxide.

11. The electronic device according to claim 8,

wherein the semiconductor layer comprises one selected from a group consisting of an amorphous semiconductor, a microcrystal semiconductor, and crystalline semiconductor layer.

12. The electronic device according to claim 8,

wherein the light-emitting device is a display device.

13. The electronic device according to claim 8, further comprising a counter substrate over the cathode,

wherein the substrate is a plastic substrate.

14. An electronic device comprising:

a light-emitting device comprising;

a substrate comprising an organic compound;

an anode over the substrate;

a first layer over the anode, the first layer generating holes;

a light emitting layer comprising a light emitting material over the first layer;

a second layer over the light emitting layer, the second layer generating electrons;

a third layer comprising metal oxide over the second layer, the third layer generating holes;

a cathode being in contact with the third layer;

a counter substrate over the cathode; and

a resin filled between the cathode and the counter substrate.

15. The electronic device according to claim 14,

wherein a display portion comprises the light-emitting device, and

wherein the substrate comprises a material selected from the group consisting of polyimide, acrylic, polyethylene terephthalate, polycarbonate, polyacrylate, and polyethersulfone.

16. The electronic device according to claim 14,

wherein the metal oxide is selected from the group consisting of vanadium oxide, molybdenum oxide, cobalt oxide, and nickel oxide.

17. The electronic device according to claim 14,

wherein the resin comprises one selected from a group consisting of polyvinyl chloride, acrylic, polyimide, an epoxy resin, a silicon resin, polyvinyl butyral, and ethylene vinylene acetate.

18. The electronic device according to claim 14,

wherein the light-emitting device is a display device.

19. The electronic device according to claim 14,

wherein a display portion comprises the light-emitting device, and

wherein the substrate is a plastic substrate.