Light-Emitting Device and Electronic Devices

• US 20100252825A1
• Filed: 06/03/2010
• Published: 10/07/2010
• Est. Priority Date: 12/15/2003
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Ikeda, Hisao, Ohara, Hiroki, Yamazaki, Shunpei, Ishitani, Tetsuji, Nakamura, Yasuo
• Granted Patent: US 8,188,655 B2
• Time in Patent Office: Days
• US Class Current: 257/40
• CPC Class Codes: H10K 2102/3031 Two-side emission, e.g. transparent OLEDs [TOLED]
• CPC Class Codes: H10K 50/86 Arrangements for improving contrast, e.g. preventing reflection of ambient light
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/35 comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 59/8791 Arrangements for improving contrast, e.g. preventing reflection of ambient light

Abstract

The present invention provides a lightweight, thin light-emitting device having a new structure which has a plurality of display screens. Further, the invention provides a dual emission type display device which can perform a pure black display and can achieve high contrast. According to the invention, at least, both electrodes of a light-emitting element (an anode and a cathode of a light-emitting element) are highly light-transmitting at the same level, and a polarizing plate or a circularly polarizing plate is provided, thereby conducting a pure black display that is a state of no light-emission and enhancing the contrast. Moreover, unevenness of color tones in displays of the both sides, which is a problem of a full-color dual emission type display device structure, can be solved according to the invention.

Claims

1. A light-emitting device comprising:

a first light-emitting element configured to emit red light;

a second light-emitting element configured to emit green light;

a third light-emitting element configured to emit blue light;

a first polarizing plate arranged on a front side of the first light-emitting element, the second light-emitting element and the third light-emitting element; and

a second polarizing plate arranged on a rear side of the first light-emitting element, the second light-emitting element and the third light-emitting element,

wherein each of the first light-emitting element, the second light-emitting element and the third light-emitting element includes;

a cathode;

a first layer containing a first organic compound;

a second layer having a hole injecting property containing a metal oxide and a second organic compound;

a light emitting layer in contact with said first layer; and

an anode in contact with the second layer,

wherein each of the anode and the cathode of the first light-emitting element, the second light-emitting element and the third light-emitting element is a light-transmitting conductive film, and

wherein the second organic compound includes an aromatic amine based compound.

2. The light-emitting device according to claim 1, wherein the light-transmitting conductive film comprises a material selected from a group consisting of indium tin oxide alloy, indium zinc oxide alloy, zinc oxide, and indium tin oxide including SiOx.

3. The light-emitting device according to claim 1, wherein the first organic compound and the second organic compound comprise the same material.

4. The light-emitting device according to claim 1, wherein the metal oxide is selected from a group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide and tungsten oxide.

5. An electronic device including the light-emitting device according to claim 1, wherein the electronic device is a personal digital assistant, a video camera, a digital camera, a digital video camera or a personal computer.

6. A light-emitting device comprising:

a first light-emitting element configured to emit red light;

a second light-emitting element configured to emit green light;

a third light-emitting element configured to emit blue light;

a first polarizing plate arranged on a front side of the first light-emitting element, second light-emitting element and the third light-emitting element;

a first quarter-wave plate arranged between the first light-emitting element and the first polarizing plate, the second light-emitting element and the first polarizing plate, and the third light-emitting element and the first polarizing plate;

a second polarizing plate arranged on a rear side of the first light-emitting element, second light-emitting element and the third light-emitting element; and

a second quarter-wave plate arranged between the first light-emitting element and the second polarizing plate, the second light-emitting element and the second polarizing plate, and the third light-emitting element and the second polarizing plate,

wherein each of the first light-emitting element, the second light-emitting element and the third light-emitting element includes;

a cathode;

a first layer containing a first organic compound;

a second layer having a hole injecting property containing a metal oxide and a second organic compound;

a light emitting layer in contact with said first layer; and

an anode in contact with the second layer,

wherein each of the anode and the cathode of the first light-emitting element, the second light-emitting element and the third light-emitting element is a light-transmitting conductive film, and

wherein the second organic compound includes an aromatic amine based compound.

7. The light-emitting device according to claim 6, wherein the light-transmitting conductive film comprises a material selected from a group consisting of indium tin oxide alloy, indium zinc oxide alloy, zinc oxide, and indium tin oxide including SiOx.

8. The light-emitting device according to claim 6, wherein the first organic compound and the second organic compound comprise the same material.

9. The light-emitting device according to claim 6, wherein the metal oxide is selected from a group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide and tungsten oxide.

10. An electronic device including the light-emitting device according to claim 6, wherein the electronic device is a personal digital assistant, a video camera, a digital camera, a digital video camera or a personal computer.

12. The light-emitting device according to claim 10, wherein the light-transmitting conductive film comprises a material selected from a group consisting of indium tin oxide alloy, indium zinc oxide alloy, zinc oxide, and indium tin oxide including SiOx.

11. A light-emitting device comprising:

a first light-emitting element configured to emit red light;

a second light-emitting element configured to emit green light;

a third light-emitting element configured to emit blue light;

a first polarizing plate arranged on a front side of the first light-emitting element, second light-emitting element and the third light-emitting element;

a first quarter-wave plate arranged between the first light-emitting element and the first polarizing plate, the second light-emitting element and the first polarizing plate, and the third light-emitting element and the first polarizing plate;

a first half-wave plate arranged between the first polarizing plate and the first quarter-wave plate;

a second polarizing plate arranged on a rear side of the first light-emitting element, second light-emitting element and the third light-emitting element;

a second quarter-wave plate arranged between the first light-emitting element and the second polarizing plate, the second light-emitting element and the second polarizing plate, and the third light-emitting element and the second polarizing plate; and

a second half-wave plate arranged between the second polarizing plate and the second quarter-wave plate,

wherein each of the first light-emitting element, the second light-emitting element and the third light-emitting element includes;

a cathode;

a first layer containing a first organic compound;

a second layer having a hole injecting property containing a metal oxide and a second organic compound;

a light emitting layer in contact with said first layer; and

an anode in contact with the second layer,

wherein each of the anode and the cathode of the first light-emitting element, the second light-emitting element and the third light-emitting element is a light-transmitting conductive film, and

wherein the second organic compound includes an aromatic amine based compound.

13. The light-emitting device according to claim 11, wherein the first organic compound and the second organic compound comprise the same material.

14. The light-emitting device according to claim 11, wherein the metal oxide is selected from a group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide and tungsten oxide.

15. An electronic device including the light-emitting device according to claim 11, wherein the electronic device is a personal digital assistant, a video camera, a digital camera, a digital video camera or a personal computer.

16. A light-emitting device comprising:

a substrate;

a plurality of light-emitting elements formed over the substrate, each of the plurality of light-emitting elements comprising;

a cathode;

a first layer containing a first organic compound;

a second layer having a hole injecting property containing a metal oxide and a second organic compound;

a light emitting layer in contact with said first layer; and

an anode in contact with the second layer,

wherein each of the anode and the cathode of the plurality of light-emitting elements is transparent to light emitted from the plurality of light-emitting elements,

wherein a first polarizing plate and a second polarizing plate are provided opposed to each other with the plurality of light-emitting elements interposed therebetween, and

wherein the second organic compound includes an aromatic amine based compound.

17. The light-emitting device according to claim 16, wherein the first organic compound and the second organic compound comprise the same material.

18. The light-emitting device according to claim 16, wherein the metal oxide is selected from a group consisting of molybdenum oxide, vanadium oxide, ruthenium oxide and tungsten oxide.

19. An electronic device including the light-emitting device according to claim 16, wherein the electronic device is a personal digital assistant, a video camera, a digital camera, a digital video camera or a personal computer.