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

作者：Wei Bin^*; Liao Ying-Jie; Liu Ji-Zhong; Lu Lin; Cao Jin; Wang Jun; Zhang Jian-Hua

来源：Chinese Physics B, 2010, 19(3): 037105.

DOI：10.1088/1674-1056/19/3/037105

• organic light-emitting diodes
• excitation mechanism
• charge trapping
• current density

This paper utilizes multilayer organic light-emitting diodes with a thin layer of dye molecules to study the mechanism 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.

• 出版日期2010-3
• 单位上海大学