Dresden 2017 – wissenschaftliches Programm
CPP 41.3: Vortrag
Mittwoch, 22. März 2017, 15:45–16:00, ZEU 260
Electron Affinity and Charge Trapping in Ternary Fullerene-based Donor:Acceptor Films for Organic Photovoltaics — •Michael Auth1, Michael Brendel1, Andreas Sperlich1, Stephan Väth1, Jens Pflaum1,2, and Vladimir Dyakonov1,2 — 1Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — 2Bayerisches Zentrum für Angewandte Energieforschung (ZAE Bayern), 97074 Würzburg
Fullerene materials for organic photovoltaics (OPV) are highly expensive, due to their elaborate purification. To determine if this step is necessary to a high degree, we investigate the influence of fullerene mixtures, i.e. unpurified fullerenes, in ternary OPV materials. As the molecule’s electron affinity determines where charge carriers reside, it also determines if unintentional molecules act as trap sites. Since electron paramagnetic resonance (EPR) addresses localised charges, we investigate photo-induced charge transfer via EPR in correlation with solar cell parameters (VOC, JSC, PCE). For polymer-fullerene blends we used the conjugated polymers P3HT or PTB7, together with the soluble fullerene derivatives PC70BM, PC60BM and IC60BA. As comparison, we furthermore investigated solar cell absorbers made of various vacuum deposited mixtures of C70 and C60 fullerenes on top of Diindenoperylene (DIP). For all configurations we compare the redistribution of electrons in the fullerene phase with the corresponding stoichiometry to determine electron affinity differences. In conjunction with solar cell parameters we are then able to determine the influence of unpurified fullerenes upon OPV.