Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Organic Semiconductors
CPP 24.10: Vortrag
Mittwoch, 13. März 2013, 12:15–12:30, H40
Probing charge carrier - exciton interactions in Diindenoperyleneby the photoluminescence response of thin film transistors — •N.H. Hansen1, C. Wunderlich1, A.K. Topczak1,2, and J. Pflaum1,3 — 1Experimental Physics VI, Julius Maximilians University of Würzburg, 97074 Würzburg — 2Center for Nanosystems Chemistry, 97074 Würzburg — 3ZAE Bayern, 97074 Würzburg
Exciton loss mechanisms play a significant role in organic devices such as organic photo-voltaic cells (OPVs) or organic light emitting diodes (OLEDs). We present a novel approach to investigate the interplay between excitons and charge carriers by means of photoluminescence (PL) measurements on organic thin film transistors (OTFT). For this purpose, the organic semiconductor Diindenoperylene was utilized as active OTFT material. The OTFT geometry benefits from a spatially defined zone for the interaction between charges and photo-generated excitons leading to an intensity reduction of the DIP photoluminescence of up to 4.5%. This effect is found to correlate with the accumulated hole carrier density below the threshold voltage and provides access to the non-radiative exciton-hole recombination rate. Taking into account the respective measurement geometry, the estimated recombination rate of about 0.3·10−10 cm3/s compares sufficiently well with data reported on single crystals [1]. From the similarity of the threshold voltage and the saturation voltage above which the quenching becomes constant, we conclude the quenching process to be preferentially mediated by trapped holes within the DIP accumulation layer. [1] N. Wakayama and D.F. Williams, J. Chem. Phys., 57(4):1770, 1972