Light emitting element and light emitting device

• US 8,922,116 B2
• Filed: 12/31/2012
• Issued: 12/30/2014
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Kumaki, Daisuke, Ikeda, Hisao, Abe, Hiroko, Seo, Satoshi
• Primary Examiner(s): Bowman, Mary Ellen
• Application Number:
  US13/731,442
• Publication Number:
  US 20130214256A1
• Time in Patent Office: 729 Days
• Field of Search: 313/501, 313/504, 313/506
• US Class Current: 313/506
• CPC Class Codes: H10K 50/14 Carrier transporting layers
• CPC Class Codes: H10K 50/155 comprising dopants
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 50/19 Tandem OLEDs
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 59/10 OLED displays
• 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 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/87 Passivation; Containers; Encapsulations
• CPC Class Codes: Y10S 428/917 Electroluminescent
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

A light emitting element of the invention includes n pieces of light emitting layers (n is a natural number) between first and second electrodes. A first layer and a second layer are provided between the m^th light emitting layer (m is a natural number of 1≦m≦n) and the m+1^th light emitting layer. The first and second layers are contacted to each other. The first layer contains a substance that transports holes easily and a substance with an electron accepting property. The second layer contains a substance that transports electrons easily and a substance with an electron donating property. Molybdenum oxide is used as the substance with the electron accepting property.

Claims

1. A light-emitting device comprising;

an anode;

a first layer over the anode, the first layer comprising a first organic compound;

a second layer over the first layer, the second layer comprising molybdenum oxide;

a third layer over the second layer, the third layer comprising a second organic compound; and

a cathode over the third layer.

2. The light-emitting device according to claim 1, wherein the first layer and the second layer are configured to emit light when a voltage is applied between the anode and the cathode.

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

wherein the first layer comprises a plurality of organic compound layers, and

wherein the first organic compound is included in one of the plurality of organic compound layers.

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

wherein the third layer comprises a plurality of organic compound layers, and

wherein the second organic compound is included in one of the plurality of organic compound layers.

5. The light-emitting device according to claim 1, wherein the first organic compound is a light-emitting material.

6. The light-emitting device according to claim 1, wherein the second organic compound is a light-emitting material.

7. The light-emitting device according to claim 1, further comprising a fourth layer between the first layer and the second layer,

wherein the fourth layer is in contact with the second layer, and

wherein the fourth layer comprises an electron-transporting material and a material selected from an alkali metal and an alkali earth metal.

8. The light-emitting device according to claim 2, wherein an emission color of the first layer is different from an emission color of the third layer.

9. The light-emitting device according to claim 8, wherein the emission color of the first layer is complementary to the emission color of the third layer.

10. The light-emitting device according to claim 3,

wherein the plurality of organic compound layers include a layer comprising a hole-transporting material and an electron acceptor with respect to the hole-transporting material, and

wherein the layer is in contact with the anode.

11. The light-emitting device according to claim 10, wherein the electron acceptor is molybdenum oxide.

12. An electronic appliance comprising the light-emitting device according to claim 1.

13. A lighting appliance comprising the light-emitting device according to claim 1.

18. The light-emitting device according to claim 1, wherein the second layer further comprises an organic compound which is mixed with the molybdenum oxide in the second layer.

19. The light-emitting device according to claim 1, wherein the second layer is spaced from both the anode and the cathode.

20. The light-emitting device according to claim 18, wherein the organic compound is an aromatic amine.

14. An electronic appliance comprising a light-emitting device, the light-emitting device comprising:

a display portion comprising a plurality of pixels arranged in a matrix form, each of the plurality of pixels comprising a transistor and a light-emitting element;

a driver circuit electrically connected to the display portion;

an external input terminal electrically connected to the driver circuit through a wiring; and

a printed wiring board attached to the external input terminal,

wherein the electronic appliance further comprises a main body to which an audio input portion, an audio output portion, an operation key, and the display portion are incorporated, and

wherein the light-emitting element comprises;

an anode;

a first layer over the anode, the first layer comprising a first organic compound;

a second layer over and in contact with the first layer, the second layer comprising molybdenum oxide;

a third layer over and in contact with the second layer, the third layer comprising a second organic compound; and

a cathode over the third layer.

15. The electronic appliance according to claim 14, wherein the electronic appliance is a mobile phone.

16. An electronic appliance comprising a light-emitting device, the light-emitting device comprising:

a display portion comprising a plurality of pixels arranged in a matrix form, each of the plurality of pixels comprising a transistor and a light-emitting element;

a driver circuit electrically connected to the display portion;

an external input terminal electrically connected to the driver circuit through a wiring; and

a printed wiring board attached to the external input terminal,

wherein the electronic appliance further comprises a main body to which the display portion is incorporated, and

wherein the light-emitting element comprises;

an anode;

a first layer over the anode, the first layer comprising a first organic compound;

a second layer over and in contact with the first layer, the second layer comprising molybdenum oxide;

a third layer over and in contact with the second layer, the third layer comprising a second organic compound; and

a cathode over the third layer.

17. The electronic appliance according to claim 16, wherein the electronic appliance is selected from a computer and a television set.