Dresden 2017 – scientific programme
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DS: Fachverband Dünne Schichten
DS 23: Organic Semiconductors (jointly with CPP/HL)
DS 23.3: Talk
Tuesday, March 21, 2017, 10:00–10:15, POT 251
Charge-exciton quenching in organic transistors — •Wouter Koopman1,2, Stefano Toffanin2, and Michele Muccini2 — 1Universität Potsdam, Potsdam, Deutschland — 2CNR-ISMN, Bologna, Italien
Organic Light-Emitting Transistors (OLETs) possess a huge potential for the design of highly integrated multifunctional optoelectronic systems and intense nanoscale light sources, such as the long-searched-for electrically pumped organic laser. In order to fulfill these promises, the efficiency and brightness of the current state-of-the-art devices have to be increased. The dominating quenching process limiting the external quantum efficiency in OLETs is charge-exciton interaction. A comprehensive understanding of this quenching process is therefore of paramount importance. The present talk reports a systematic investigation of charge-exciton interaction in organic transistors employing time-resolved photoluminescence electro-modulation (PLEM) spectroscopy on the picosecond timescale. The results show that the injected charges reduce the exciton radiative recombination in two ways: (i) charges may prevent the generation of excitons and (ii) charges activate a further non-radiative channel for the exciton decay. Moreover, the transient PLEM measurements clearly reveal that not only trapped charges, as it is was already reported in literature, but rather the entire injected charge density contributes to the quenching of the exciton population. Finally, lessons for the design of high-efficiency OLET are disused.