Charge-Induced Luminescence Quenching in Organic Light-Emitting Diodes

Autor:	and Alfred P. Marchetti, Jerome R. Lenhard, Terri L. Haskins, Ralph H. Young, Lewis J. Rothberg, A. Chowdhury
Rok vydání:	2004
Předmět:	Photoluminescence Quenching (fluorescence) Chemistry General Chemical Engineering Doping Materials Chemistry OLED Quantum efficiency General Chemistry Singlet state Photochemistry Luminescence Fluorescence
Zdroj:	Chemistry of Materials. 16:4675-4680
ISSN:	1520-5002 0897-4756
DOI:	10.1021/cm049538k
Popis:	We use charge modulation spectroscopy (CMS) in model holes-only devices to address the reason for decreasing quantum efficiency with increasing drive current in organic light-emitting diodes based on Alq3 doped with the red dye DCJTB. We are able to measure the density of DCJTB+ and correlate it with the diminution of the photoluminescence. The magnitude and DCJTB+ density dependence of the photoluminescence reduction are roughly consistent with quenching of the singlet-excited-state of DCJTB via Forster energy transfer to DCJTB+. At low DCJTB+ densities, the quenching is stronger than theory would predict and we propose that singlet energy transport among DCJTB molecules extends the distance over which quenching by DCJTB+ is effective. Since the Forster mechanism can be responsible for charge-induced PL quenching as large as 70% even though DCJTB+ is very weakly absorbing where DCJTB singlets fluoresce, it may be difficult to avoid quenching by electrically generated species.
Databáze:	OpenAIRE
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