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

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...

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Bibliographic Details
Published in:Chinese physics B 2010-03, Vol.19 (3), p.450-455
Main Author: 魏斌 廖英杰 刘纪忠 路林 曹进 王军 张建华
Format: Article
Language:English
Subjects:
Charge
Current density
Dyes
Electric charge
Electric fields
Emittance
Light-emitting diodes
Trapping
依赖性
掺杂剂
有机发光二极管
染料种类
电流密度
荧光灯
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Summary: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.
ISSN:1674-1056
2058-3834
DOI:10.1088/1674-1056/19/3/037105