Dependence of charge trapping of fluorescent and phosphorescent dopants in organic light-emitting diodes on the dye species and current density  

作　　者：魏斌 廖英杰 刘纪忠 路林 曹进 王军 张建华 

机构地区：[1]Key Laboratory of Advanced Display and System Applications,Ministry of Education, Shanghai University

出　　处：《Chinese Physics B》2010年第3期450-455,共6页中国物理B（英文版）

基　　金：Project supported by the Key Project of Shanghai Education Committee (Grant No. 08ZZ42);Science and Technology Commission of Shanghai Municipal (Grant Nos. 08PJ14053,08DZ1140702 and 08520511200)

摘　　要：This paper utilizes multilayer organic light-emitting diodes with a thin layer of dye molecules to study the mech- anism of charge trapping under different electric regimes. It demonstrates that the carrier trapping was independent of the current density in devices using fluorescent material as the emitting molecule while this process was exactly opposite when phosphorescent material was used. The triplet-triplet annihilation and dissociation of excitons into free charge carriers was considered to contribute to the decrease in phosphorescent emission under high electric fields. Moreover, the fluorescent dye molecule with a lower energy gap and ionized potential than the host emitter was observed to facilitate the carrier trapping mechanism, and it would produce photon emission.This paper utilizes multilayer organic light-emitting diodes with a thin layer of dye molecules to study the mech- anism of charge trapping under different electric regimes. It demonstrates that the carrier trapping was independent of the current density in devices using fluorescent material as the emitting molecule while this process was exactly opposite when phosphorescent material was used. The triplet-triplet annihilation and dissociation of excitons into free charge carriers was considered to contribute to the decrease in phosphorescent emission under high electric fields. Moreover, the fluorescent dye molecule with a lower energy gap and ionized potential than the host emitter was observed to facilitate the carrier trapping mechanism, and it would produce photon emission.

关 键 词：organic light-emitting diodes excitation mechanism charge trapping current density 

分 类 号：TN312.8[电子电信—物理电子学] TQ153.2[化学工程—电化学工业]