Light-emitting EL display device

• US 6,641,933 B1
• Filed: 09/21/2000
• Issued: 11/04/2003
• Est. Priority Date: 09/24/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Konuma, Toshimitsu, Yamazaki, Shunpei, Mizukami, Mayumi
• Primary Examiner(s): Kelly, Cynthia H.
• Assistant Examiner(s): Garrett, Dawn L.
• Application Number:
  US09/667,493
• Time in Patent Office: 1,139 Days
• Field of Search: 428/690, 428/917, 313/504, 313/500, 313/502, 313/506, 313/505, 427/66
• US Class Current: 428/690
• 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 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. An EL display device having pixels each provided with an EL element, wherein the EL element includes a thin film comprising a light-emitting organic compound, and the thin film includes ionic impurities and has a volume resistivity of 3×

10¹⁰ Ω

cm or larger, and the concentration of the ionic impurities is 0.1 ppm or lower.

2. A device according to claim 1, wherein the ionic impurities are sodium or potassium.

3. An electronic apparatus comprising, as a display portion, an EL display device according to claim 1.

4. An EL display device having pixels each provided with a thin film transistor (TFT) and an EL element connected to the TFT, wherein the EL element includes a thin film comprising a light-emitting organic compound, and the thin film includes ionic impurities and has a volume resistivity of 3×

10¹⁰ Ω

cm or larger, and the concentration of the ionic impurities is 0.1 ppm or lower.

5. A device according to claim 4, wherein the ionic impurities are sodium or potassium.

6. An electronic apparatus comprising, as a display portion, an EL display device according to claim 4.

7. An EL display device having pixels each provided with an EL element, comprising:

anodes arranged in stripes;

cathodes arranged in stripes to be orthogonal to the anode; and

a thin film made of a light-emitting organic compound provided between the anodes and the cathodes,

wherein the thin film comprises ionic impurities and has a volume resistivity of 3×

10¹⁰ Ω

cm or larger, and

wherein the concentration of the ionic impurities is 0.1 ppm or lower.

8. A device according to claim 7, wherein the ionic impurities are sodium or potassium.

9. An electronic apparatus comprising, as a display portion, an EL display device according to claim 7.

10. A method for fabricating an EL display device having pixels each provided with an EL element, comprising:

forming a thin film comprising a light-emitting organic compound,

wherein the thin film includes ionic impurities and has a volume resistivity of 3×

10¹⁰ Ω

cm or larger, and

wherein the concentration of the ionic impurities is 0.1 ppm or lower.

11. An EL display device having pixels each provided with an EL element, wherein the EL element includes a thin film comprising a light-emitting organic compound, and the thin film includes ionic impurities at the concentration of 0.1 ppm or lower and has a volume resistivity of 1×

10¹¹ to 1×

10¹² Ω

cm.

12. A device according to claim 11, wherein the ionic impurities are sodium or potassium.

13. A electronic apparatus comprising, as a display portion, an EL display device according to claim 11.

14. An EL display device having pixels each provided with a TFT and an EL element connected to the TFT, wherein the EL element includes a thin film comprising a light-emitting organic compound, and the thin film includes ionic impurities at the concentration of 0.1 ppm or lower and has a volume resistivity of 1×

10¹¹ to 1×

10¹² Ω

cm.

15. A device according to claim 14, wherein the ionic impurities are sodium or potassium.

16. An electronic apparatus comprising, as a display portion, an EL display device according to claim 14.

17. An EL display device having pixels each provided with an EL element, comprising:

anodes arranged in stripes;

cathodes arranged in stripes to be orthogonal to the anode; and

a thin film made of a light-emitting organic compound provided between the anodes and the cathodes,

wherein the thin film comprises ionic impurities and has a volume resistivity of 1×

10¹¹ to 1×

10¹² Ω

cm, and

wherein the concentration of the ionic impurity is 0.1 ppm or lower

18. A device according to claim 17, wherein the ionic impurities are sodium or potassium.

19. An electronic apparatus comprising, as a display portion, an EL display device according to claim 17.

20. A method for fabricating an EL display device having pixels each provided with an EL element, comprising:

forming a thin film comprising a light-emitting organic compound,

wherein the thin film includes ionic impurities and has a volume resistivity of 1×

10¹¹ to 1×

10¹² Ω

cm, and

wherein the concentration of the ionic impurities is 0.1 ppm or lower.