Light emitting device having organic compound

• US 8,350,469 B2
• Filed: 10/25/2011
• Issued: 01/08/2013
• Est. Priority Date: 04/05/2002
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Kuwabara, Hideaki
• Primary Examiner(s): Guharay, Karabi
• Application Number:
  US13/280,632
• Publication Number:
  US 20120037899A1
• Time in Patent Office: 441 Days
• Field of Search: 313/504, 313/506
• US Class Current: 313/506
• CPC Class Codes: H10K 50/87 Arrangements for heating or cooling
• CPC Class Codes: H10K 59/8794 Arrangements for heating and cooling
• CPC Class Codes: H10K 85/146 poly N-vinylcarbazol; Derivatives thereof
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: H10K 85/649 Aromatic compounds comprising a hetero atom
• CPC Class Codes: H10K 85/6565 Oxadiazole compounds

Abstract

When a light emitting element is actuated to allow the light emission, the generation of Joule heat occurs, leading to the decomposition or crystallization of an organic compound to cause the degradation of the light emitting device. Therefore, a light emitting element of the present invention is provided for effecting removing or decreasing the generation of heat. In the present invention, between two electrodes, layers having organic compounds and carbon-based thin films are alternatively laminated one after another for stepping down the driving voltage in the light emitting element using the tunnel effect. In addition, a carbon-based thin film is placed on a film containing an organic compound, so that it prevents the electric field from being locally concentrated and also prevents the generation of short-circuit between the anode and the cathode.

Claims

1. A light emitting device comprising:

a light emitting element comprising;

a first electrode;

a first light emitting layer over the first electrode;

a carbon-based film over the first light emitting layer;

a second light emitting layer over the carbon-based film; and

a second electrode over the second light emitting layer;

wherein the carbon-based film is in contact with the first light emitting layer and the second light emitting layer, and

wherein the carbon-based film has a visible light transmittance of 50 to 100%.

2. A light emitting device according to claim 1, wherein the carbon-based film has larger band gap than the first light emitting layer and the second light emitting layer.

3. A light emitting device according to claim 1, wherein the first electrode and the second electrode are arranged such that an electron passes through the carbon-based film by applying a voltage between the first electrode and the second electrode.

4. A light emitting device according to claim 1, wherein the carbon-based film is an insulator or diamond like carbon.

5. A light emitting device according to claim 1, wherein the carbon-based film is a potential barrier.

6. A light emitting device according to claim 1, further comprising a carbon-based film between the second light emitting layer and the second electrode.

7. A light emitting device according to claim 1, further comprising a carbon-based film between the first light emitting layer and the first electrode.

8. A light emitting device according to claim 1, wherein the light emitting device is a passive matrix electroluminescence display device.

9. A light emitting device according to claim 1, wherein each of the first light emitting layer and the second light emitting layer includes an organic material.

10. A light emitting device according to claim 1, further comprising a color filter over the second electrode, the color filter and the light emitting element overlap with each other,

wherein the light emitting element emits white light.

11. A light emitting device comprising:

a light emitting element comprising;

a first electrode;

a first light emitting layer over the first electrode;

a carbon-based film over the first light emitting layer;

a second light emitting layer over the carbon-based film; and

a second electrode over the second light emitting layer; and

a color filter, the color filter and the light emitting element overlap with each other,

wherein the carbon-based film is in contact with the first light emitting layer and the second light emitting layer, and

wherein the light emitting element emits white light.

12. A light emitting device according to claim 11, wherein the carbon-based film has larger band gap than the first light emitting layer and the second light emitting layer.

13. A light emitting device according to claim 11, wherein the first electrode and the second electrode are arranged such that an electron passes through the carbon-based film by applying a voltage between the first electrode and the second electrode.

14. A light emitting device according to claim 11, wherein the carbon-based film is an insulator or diamond like carbon.

15. A light emitting device according to claim 11, wherein the carbon-based film is a potential barrier.

16. A light emitting device according to claim 11, further comprising a carbon-based film between the second light emitting layer and the second electrode.

17. A light emitting device according to claim 11, further comprising a carbon-based film between the first light emitting layer and the first electrode.

18. A light emitting device according to claim 11, wherein the light emitting device is a passive matrix electroluminescence display device.

19. A light emitting device according to claim 11, wherein each of the first light emitting layer and the second light emitting layer includes an organic material.

20. A light emitting device according to claim 11, wherein the carbon-based film has a visible light transmittance of 50 to 100%.