Performance Improvement of Organic Light-Emitting Device by Using Metal-Dopant Technology and a Red Dye

• Main Authors: Meng-Hsiu Wu, 吳孟修
• Other Authors: 李君浩
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/80577158148549612393

碩士 === 國立臺灣大學 === 光電工程學研究所 === 93 === In this thesis, the OLED performance of novel cesium (Cs) doped 4,4''-bis(5-phenyl-[1,3,4]oxadiazol-2-yl)-2,2''-dinaphthylbiphenyl (bis-OXD), a metal-doped electron transport layer (MD-ETL), is reported herein. Cs is a heavy alkali atom and difficult to diffuse in an organic matrix. The metal quenching effect is therefore reduced in a long-term operation. The host material, bis-OXD, exhibits a high glass transition temperature (Tg) of 147 oC. The average roughness of the thin film is small when compared with other derivatives. The leakage current of the corresponding OLED devices is low. By using a highly reflective and conductive silver cathode, an OLED with a 2.59 V reduction in driving voltage, a 47.3% increase in current efficiency, and a 3.14 times enhancement in operation lifetime was demonstrated. We use a new red dye organic material to fabricate an OLED. Such a device exhibits a higher color-purity as compared with that with the conventional red dopant material, 4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl)-4H-pyran (DCJTB), under the same doping concentration. There is no current-induced fluorescence quenching on the electroluminance of the device with this red dopant material. The current efficiency of the red device can be improved by six times with insertion of a hole blocking layer between the emitting layer and electron transport layer.