Light emitting element and light emitting device using the element

• US 8,536,569 B2
• Filed: 12/09/2011
• Issued: 09/17/2013
• Est. Priority Date: 05/21/2004
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Seo, Satoshi
• Primary Examiner(s): Mandala, Victor A
• Application Number:
  US13/316,079
• Publication Number:
  US 20120205684A1
• Time in Patent Office: 648 Days
• Field of Search: 257/40, 257/79, 257/88, 257/89, 257/E51.018, 257/E51.022
• US Class Current: 257/40
• CPC Class Codes: H10K 50/125 specially adapted for multicolour light emission, e.g. for emitting white light
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]

Abstract

A first light emitting element 310 and a second light emitting element 320 are serially laminated over a substrate 300. The first light emitting element 310 has a light emitting layer 312 between a first anode 311 and a first cathode 313, and the second light emitting element 320 has a light emitting layer 322 between a second anode 321 and a second cathode 323. Here, the light emitting layer 312 shows a first emission spectrum 330 having peaks both in a blue to blue green wavelength range and in a yellow to orange wavelength range, and the light emitting layer 322 shows a second emission spectrum 340 having peaks both in a blue green to green wavelength range and in an orange to red wavelength range.

Claims

1. A light emitting device comprising:

a thin film transistor over a substrate, the thin film transistor comprising;

a semiconductor film over the substrate;

an insulating film adjacent to the semiconductor film; and

a gate electrode adjacent to the semiconductor film with the insulating film interposed therebetween;

a first light emitting element having a first light emitting layer including a light emitting organic compound; and

a second light emitting element having a second light emitting layer including a light emitting organic compound,

wherein the first light emitting layer and the second light emitting layer are overlapped with each other, and

wherein the first light emitting element shows a first emission spectrum having at least two peaks and the second light emitting element shows a second emission spectrum having a peak in a different position from positions of the two peaks.

2. The light emitting device according to claim 1, wherein the second emission spectrum has at least two peaks.

9. The light emitting device according to any one of claims 1, 3, 5 and 7, wherein the first light emitting layer comprises a third light emitting layer and a fourth light emitting layer which shows a different emission color from an emission color of the third light emitting layer.

10. The light emitting device according to claim 9, wherein the third light emitting layer is in contact with the fourth light emitting layer.

11. The light emitting device according to any one of claims 1, 3, 5 and 7, wherein the second light emitting layer comprises a fifth light emitting layer and a sixth light emitting layer which shows a different emission color from an emission color of the fifth light emitting layer.

12. The light emitting device according to claim 11, wherein the fifth light emitting layer is in contact with the sixth light emitting layer.

13. The light emitting device according to any one of claims 1, 3, 5 and 7, further comprising a color filter,

wherein a white emission color is shown by the first emission spectrum and the second emission spectrum, and

wherein the color filter is arranged to change a chromaticity of the white emission color.

14. The light emitting device according to any one of claims 1, 3, 5 and 7,

wherein the first light emitting layer is formed by a spin coating method, an ink-jet method, or a dip coating method, and

wherein the second light emitting layer is formed by a vacuum evaporation method.

3. A light emitting device comprising:

a thin film transistor over a substrate, the thin film transistor comprising;

a semiconductor film over the substrate;

an insulating film adjacent to the semiconductor film; and

a gate electrode adjacent to the semiconductor film with the insulating film interposed therebetween;

a first light emitting element having a first light emitting layer including a light emitting organic compound; and

a second light emitting element having a second light emitting layer including a light emitting organic compound,

wherein the first light emitting layer and the second light emitting layer are overlapped with each other, and

wherein the first light emitting element shows a first emission color including two kinds of emission colors having a complementary color relationship and the second light emitting element shows a second emission color different from the two kinds of emission colors.

4. The light emitting device according to claim 3, wherein the second emission color includes two kinds of emission colors having a complementary color relationship, and the two kinds of emission colors of the second emission color are different from the two kinds of emission colors of the first emission color.

5. A light emitting device comprising:

a thin film transistor over a substrate, the thin film transistor comprising;

a semiconductor film over the substrate;

an insulating film adjacent to the semiconductor film; and

a gate electrode adjacent to the semiconductor film with the insulating film interposed therebetween;

a first light emitting element having a first light emitting layer including a light emitting organic compound; and

a second light emitting element having a second light emitting layer including a light emitting organic compound,

wherein the first light emitting layer and the second light emitting layer are overlapped with each other, and

wherein the first light emitting element shows a first emission spectrum having peaks in a blue to blue green wavelength range and in a yellow to orange wavelength range and the second light emitting element shows a second emission spectrum having a peak in a different position from positions of the peaks.

6. The light emitting device according to claim 5, wherein the second emission spectrum is an emission spectrum having peaks in a blue green to green wavelength range and in an orange to red wavelength range.

7. A light emitting device comprising:

a thin film transistor over a substrate, the thin fihn transistor comprising;

a semiconductor film over the substrate;

an insulating film adjacent to the semiconductor film; and

a gate electrode adjacent to the semiconductor film with the insulating film interposed therebetween;

a first light emitting element having a first light emitting layer including a light emitting organic compound; and

a second light emitting element having a second light emitting layer including a light emitting organic compound,

wherein the first light emitting layer and the second light emitting layer are overlapped with each other, and

wherein the first light emitting element shows a first emission spectrum having peaks in a wavelength range from 430 nm to 480 nm and in a wavelength range from 550 nm to 600 nm and the second light emitting element shows a second emission spectrum having a peak in a different position from positions of the peaks.

8. The light emitting device according to claim 7, wherein the second emission spectrum is an emission spectrum having peaks in a wavelength range from 480 nm to 550 nm and in a wavelength range from 600 nm to 680 nm.

15. A lighting device comprising:

a first light emitting element having a first light emitting layer including a light emitting organic compound; and

a second light emitting element having a second light emitting layer including a light emitting organic compound,

wherein the first light emitting layer and the second light emitting layer are overlapped with each other, and

wherein the first light emitting layer comprises a third light emitting layer and a fourth light emitting layer which shows a different emission color from an emission color of the third light emitting layer.

16. The lighting device according to claim 15, wherein the third light emitting layer is in contact with the fourth light emitting layer.

17. The lighting device according to claim 15, wherein the second light emitting layer comprises a fifth light emitting layer and a sixth light emitting layer which shows a different emission color from an emission color of the fifth light emitting layer.

18. The lighting device according to claim 17, wherein the fifth light emitting layer is in contact with the sixth light emitting layer.

21. The lighting device according to claim 15 or 19, wherein the lighting device further comprises a color filter.

22. The lighting device according to claim 15 or 19,

wherein the lighting device shows a white emission color.

23. The lighting device according to claim 15 or 19,

wherein the first light emitting element shows a first emission spectrum having at least two peaks and the second light emitting element shows a second emission spectrum having a peak in a different position from positions of the two peaks.

24. The lighting device according to claim 15 or 19,

wherein the first light emitting layer is formed by a spin coating method, an ink-jet method, or a dip coating method, and

wherein the second light emitting layer is formed by a vacuum evaporation method.

19. A lighting device comprising:

a first light emitting element having a first light emitting layer including a light emitting organic compound; and

a second light emitting element having a second light emitting layer including a light emitting organic compound,

wherein the first light emitting layer and the second light emitting layer are overlapped with each other, and

wherein the second light emitting layer comprises a fifth light emitting layer and a sixth light emitting layer which shows a different emission color from an emission color of the fifth light emitting layer.

20. The lighting device according to claim 19, wherein the fifth light emitting layer is in contact with the sixth light emitting layer.