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

• US 20040079923A1
• Filed: 10/15/2003
• Published: 04/29/2004
• Est. Priority Date: 09/24/1999
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Konuma, Toshimitsu, Yamazaki, Shunpei, Mizukami, Mayumi
• Granted Patent: US 7,112,374 B2
• Time in Patent Office: Days
• US Class Current: 252/301.16
• 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. A light-emitting organic compound comprising ionic impurities at the oncentration of 0.1 ppm or lower.

2. A light-emitting organic compound according to claim 1, wherein the ionic impurities are sodium or potassium.

3. A light-emitting organic compound comprising ionic impurities at the concentration of 0.01 ppm or lower.

4. A light-emitting organic compound according to claim 3, wherein the ionic impurities are sodium or potassium.

5. A method for forming a light-emitting organic compound, comprising the step of performing a purification process until ionic impurities contained in a light-emitting organic compound is reduced to a concentration of 0.1 ppm or lower.

6. A method according to claim 5, wherein the purification process for the light-emitting organic compound is performed by means of a process selected from a zone purification method, a recrystallization method, a reprecipitation process, a sublimation purification method, a filtration method, a column chromatography method, a high-performance liquid chromatography method, and a dialysis method.

7. A method according to claim 5, wherein the light-emitting organic compound is a high-molecular compound purified by means of a dialysis method.

8. A method according to claim 5, wherein the ionic impurities are sodium or potassium.

9. A method for forming a light-emitting organic compound, wherein the purification process is continued to be performed until ionic impurities contained in the light-emitting organic compound is reduced to a concentration of 0.01 ppm or lower.

10. A method according to claim 9, wherein the purification process for the light-emitting organic compound is performed by means of a process selected from a zone purification method, a recrystallization method, a reprecipitation process, a sublimation purification method, a filtration method, a column chromatography method, a high-performance liquid chromatography method, and a dialysis method.

11. A method according to claim 9, wherein the light-emitting organic compound is a high-molecular compound purified by means of a dialysis method.

12. A method according to claim 9, wherein the ionic impurities are sodium or potassium.