Light-emitting organic compound and EL display device utilizing the same

• US 9,425,403 B2
• Filed: 04/10/2014
• Issued: 08/23/2016
• Est. Priority Date: 09/24/1999
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamazaki, Shunpei, Konuma, Toshimitsu, Mizukami, Mayumi
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): FAROKHROOZ, FATIMA N
• Application Number:
  US14/249,649
• Publication Number:
  US 20140221597A1
• Time in Patent Office: 866 Days
• Field of Search: 313498-512, 315/169.1, 315/169.3, 428690-691, 428/917, 438 26- 29, 438/34, 438/82, 427/66, 427532-535, 427/539
• US Class Current: 1/1
• CPC Class Codes: H10K 2102/3026 Top emission
• CPC Class Codes: H10K 50/11 characterised by the electroluminescent [EL] layers
• CPC Class Codes: H10K 50/84 Passivation; Containers; Encapsulations
• CPC Class Codes: H10K 50/8423 Metallic sealing arrangements
• CPC Class Codes: H10K 50/8426 Peripheral sealing arrangements, e.g. adhesives, sealants
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 50/846 comprising getter material or desiccants
• CPC Class Codes: H10K 50/865 comprising light absorbing layers, e.g. light-blocking layers
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: H10K 59/12 Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/38 comprising colour filters or colour changing media [CCM]
• CPC Class Codes: H10K 59/874 including getter material or desiccant
• CPC Class Codes: H10K 59/8792 comprising light absorbing layers, e.g. black layers
• CPC Class Codes: H10K 71/311 Purifying organic semiconductor materials
• CPC Class Codes: H10K 85/111 comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
• CPC Class Codes: H10K 85/114 Poly-phenylenevinylene; Derivatives thereof
• CPC Class Codes: H10K 85/324 comprising aluminium, e.g. Alq3
• CPC Class Codes: H10K 85/60 Organic compounds having low molecular weight H10K85/10 - H10K85/50 take precedence
• CPC Class Codes: Y10S 428/917 Electroluminescent

Abstract

By repeating a purification process of a light-emitting organic compound several times, a thin film made of the light-emitting organic compound to be used in an EL display device contains ionic impurities at the concentration of 0.1 ppm or lower and has a volume resistivity in the range of 3×10¹⁰ Ωcm or larger. By using such a thin film as a light-emitting layer in the EL device, a current caused by reasons other than the carrier recombination can be prevented from flowing through the thin film, and deterioration caused by unnecessary heat generation can be suppressed. Accordingly, it is possible to obtain an EL display device with high reliability.

Claims

1. A light-emitting device comprising:

a substrate;

a transistor over the substrate;

a first electrode over the transistor;

a layer comprising a compound comprising an element selected from Li, Ca, Ba, Sr, and Cs over the first electrode;

a light-emitting layer comprising a light-emitting organic compound over the layer;

a second electrode over the light-emitting layer;

a color filter over the second electrode; and

a cover member over the color filter,

wherein the substrate and the cover member are bonded to each other by a sealing material,

wherein a space surrounded by the substrate, the cover member, and the sealing material comprises an inert gas, and

wherein a volume resistivity of the light-emitting layer is in a range of 1×

10¹¹ to 1×

10¹³ Ω

cm.

2. The light-emitting device according to claim 1, wherein the layer is in contact with the first electrode.

3. The light-emitting device according to claim 1, wherein the compound is any one of LiF, Li₂O, BaF₂, BaO, CaF₂, CaO, SrO, and Cs₂O.

4. The light-emitting device according to claim 1, wherein the first electrode is a cathode.

5. The light-emitting device according to claim 1, wherein the color filter comprises barium oxide.

6. The light-emitting device according to claim 1, wherein the inert gas is noble gas or nitrogen gas.

22. The light-emitting device according to claim 1, wherein the light-emitting organic compound has a molecular weight in a range of 8×

10² to 2×

10⁶ g/mol.

23. The light-emitting device according to claim 1, wherein the light-emitting organic compound has a molecular weight in a range of 1×

10⁴ to 1×

10⁵ g/mol.

7. A light-emitting device comprising:

a substrate;

a transistor over the substrate;

a first electrode over the transistor;

a layer comprising a compound comprising an element selected from Li, Ca, Ba, Sr, and Cs over the first electrode;

a light-emitting layer comprising a light-emitting organic compound over the layer;

a second electrode over the light-emitting layer;

a color filter over the second electrode; and

a cover member over the color filter,

wherein the substrate and the cover member are bonded to each other by a sealing material,

wherein a space surrounded by the substrate, the cover member, and the sealing material comprises an inert liquid, and

wherein a volume resistivity of the light-emitting layer is in a range of 1×

10¹¹ to 1×

10¹³ Ω

cm.

8. The light-emitting device according to claim 7, wherein the layer is in contact with the first electrode.

9. The light-emitting device according to claim 7, wherein the compound is any one of LiF, Li₂O, BaF₂, BaO, CaF₂, CaO, SrO, and Cs₂O.

10. The light-emitting device according to claim 7, wherein the first electrode is a cathode.

11. The light-emitting device according to claim 7, wherein the color filter comprises barium oxide.

12. The light-emitting device according to claim 7, wherein the inert liquid is crown ether.

24. The light-emitting device according to claim 7, wherein the light-emitting organic compound has a molecular weight in a range of 8×

10² to 2×

10⁶ g/mol.

25. The light-emitting device according to claim 7, wherein the light-emitting organic compound has a molecular weight in a range of 1×

10⁴ to 1×

10⁵ g/mol.

13. A light-emitting device comprising:

a substrate;

a transistor over the substrate;

a first electrode over the transistor;

a layer comprising a compound comprising an element selected from Li, Ca, Ba, Sr, and Cs over the first electrode;

a light-emitting layer comprising a light-emitting organic compound over the layer;

a second electrode over the light-emitting layer;

a color filter over the second electrode; and

a cover member over the color filter,

wherein the substrate and the cover member are bonded to each other by a sealing material,

wherein a space surrounded by the substrate, the cover member, and the sealing material comprises an adhesive material, and

wherein a volume resistivity of the light-emitting layer is in a range of 1×

10¹¹ to 1×

10¹³ Ω

cm.

14. The light-emitting device according to claim 13, wherein the layer is in contact with the first electrode.

15. The light-emitting device according to claim 13, wherein the compound is any one of LiF, Li₂O, BaF₂, BaO, CaF₂, CaO, SrO, and Cs₂O.

16. The light-emitting device according to claim 13, wherein the first electrode is a cathode.

17. The light-emitting device according to claim 13, wherein the color filter comprises barium oxide.

26. The light-emitting device according to claim 13, wherein the light-emitting organic compound has a molecular weight in a range of 8×

10² to 2×

10⁶ g/mol.

27. The light-emitting device according to claim 13, wherein the light-emitting organic compound has a molecular weight in a range of 1×

10⁴ to 1×

10⁵ g/mol.

18. A light-emitting device comprising:

a substrate;

a transistor over the substrate;

a first electrode over the transistor;

a light-emitting layer comprising a light-emitting organic compound over the first electrode; and

a second electrode over the light-emitting layer;

wherein a volume resistivity of the light-emitting layer is in a range of 1×

10¹¹ to 1×

10¹³ Ω

cm.

19. The light-emitting device according to claim 18, further comprising:

a color filter over the second electrode; and

a cover member over the color filter,

wherein the substrate and the cover member are bonded to each other by a sealing material, and

wherein a space surrounded by the substrate, the cover member, and the sealing material comprises an inert gas.

20. The light-emitting device according to claim 18, further comprising:

a color filter over the second electrode; and

a cover member over the color filter,

wherein the substrate and the cover member are bonded to each other by a sealing material, and

wherein a space surrounded by the substrate, the cover member, and the sealing material comprises an inert liquid.

21. The light-emitting device according to claim 18, further comprising:

a color filter over the second electrode; and

a cover member over the color filter,

wherein the substrate and the cover member are bonded to each other by a sealing material, and

wherein a space surrounded by the substrate, the cover member, and the sealing material comprises an adhesive material.