Light emitting device

• US 20090115348A1
• Filed: 04/11/2008
• Published: 05/07/2009
• Est. Priority Date: 08/28/2000
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Ikeda, Hisao, Nishi, Takeshi, Yamazaki, Shunpei, Mizukami, Mayumi
• Granted Patent: US 8,049,418 B2
• Time in Patent Office: Days
• US Class Current: 315/297
• CPC Class Codes: H10K 2101/10 Triplet emission
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 2102/351 Thickness
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 50/14 Carrier transporting 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 59/35 comprising red-green-blue [RGB] subpixels
• CPC Class Codes: H10K 71/00 Manufacture or treatment specially adapted for the organic devices covered by this subclass
• 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: Y10S 428/917 Electroluminescent

Abstract

The luminance of different colors of light emitted from EL elements in a pixel portion of a light emitting device is equalized and the luminance of light emitted from the EL elements is raised. The pixel portion of the light emitting device has EL elements whose EL layers contain triplet compounds and EL elements whose EL layers contain singlet compounds in combination. The luminance of light emitted from the plural EL elements is thus equalized. Furthermore, a hole transporting layer has a laminate structure to thereby cause the EL elements to emit light of higher luminance.

Claims

1. A light emitting device comprising:

a substrate;

a first EL element formed over the substrate for emitting a light of a first color, the first EL element including a first EL layer comprising a first triplet compound;

a second EL element formed over the substrate for emitting a light of a second color which is different from the first color, the second EL element including a second EL layer comprising a second triplet compound; and

a third EL element formed over the substrate for emitting a light of a third color which is different from the first and second colors, the third EL element including a third EL layer comprising a third triplet compound over the substrate,

wherein at least one of the first, second, and third EL layers comprises a plurality of hole transporting layers.

2. A light emitting device according to claim 1,

wherein the first color is red,

wherein the second color is blue, and

wherein the third color is green.

3. A light emitting device according to claim 1, wherein one of the plurality of hole transporting layers includes at least a layer containing α

-NPD.

4. A light emitting device according to claim 3, wherein the layer containing α

-NPD is in contact with a light emitting layer.

5. A light emitting device according to claim 1, wherein at least one of the first, second, and the third triplet compound includes iridium.

6. An electric appliance comprising the light emitting device according to claim 1, wherein the electric appliance is selected from the group consisting of a display device, a video camera, a head mounted display, an image reproducing device equipped with a recording medium, a goggle type display, a personal computer, a cellular phone, an audio reproducing device, and a digital camera.

7. A light emitting device comprising:

a first substrate;

a second substrate;

a flexible printed circuit;

a pixel portion including a first thin film transistor over the first substrate;

a driver circuit including a second thin film transistor over the second substrate;

wherein the pixel portion comprises a first EL element for emitting a light of a first color, a second EL element for emitting a light of a second color, and the third EL element for emitting a light of a third color,

wherein the first EL element includes a first EL layer comprising a first triplet compound,

wherein the second EL element comprises a second EL layer comprising a second triplet compound,

wherein the third EL element comprises a third EL element comprising a third triplet compound,

wherein the second color is different from the first color,

wherein the third color is different from the first and second colors,

wherein at least one of the first, second, and third EL layers comprises a plurality of hole transporting layers, and

wherein the first substrate and the second substrate are connected through the flexible printed circuit.

8. A light emitting device according to claim 7,

wherein the first color is red,

wherein the second color is blue, and

wherein the third color is green.

9. A light emitting device according to claim 7, wherein one of the plurality of hole transporting layers includes at least a layer containing α

-NPD.

10. A light emitting device according to claim 9, wherein the layer containing α

-NPD is in contact with a light emitting layer.

11. A light emitting device according to claim 7, wherein at least one of the first, second, and the third triplet compound includes iridium.

12. An electric appliance comprising the light emitting device according to claim 7, wherein the electric appliance is selected from the group consisting of a display device, a video camera, a head mounted display, an image reproducing device equipped with a recording medium, a goggle type display, a personal computer, a cellular phone, an audio reproducing device, and a digital camera.

13. A light emitting device comprising:

a substrate;

a pixel portion including a first thin film transistor over the substrate;

a driver circuit including a second thin film transistor over the substrate;

wherein the pixel portion comprises a first EL element for emitting a light of a first color, a second EL element for emitting a light of a second color, and a third EL element for emitting a light of a third color,

wherein the first EL element comprises a first EL layer comprising a first triplet compound,

wherein the second EL element comprises a second EL layer comprising a second triplet compound,

wherein the third EL element comprises a third EL layer comprising a third triplet compound,

wherein the second color is different from the first color,

wherein the third color is different from the first and second colors, and

wherein at least one of the first, second, and third EL layers comprises a plurality of hole transporting layers.

14. A light emitting device according to claim 13,

wherein the first color is red,

wherein the second color is blue, and

wherein the third color is green.

15. A light emitting device according to claim 13, wherein one of the plurality of hole transporting layers includes at least a layer containing α

-NPD.

16. A light emitting device according to claim 15, wherein the layer containing α

-NPD is in contact with a light emitting layer.

17. A light emitting device according to claim 13, wherein at least one of the first, second, and the third triplet compound includes iridium.

18. An electric appliance comprising the light emitting device according to claim 13, wherein the electric appliance is selected from the group consisting of a display device, a video camera, a head mounted display, an image reproducing device equipped with a recording medium, a goggle type display, a personal computer, a cellular phone, an audio reproducing device, and a digital camera.