Dresden 2017 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 41: Organic Electronics and Photovoltaics IV: OPV (joint session CPP/DS/HL, organized by CPP)

CPP 41.3: Talk

Wednesday, March 22, 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 Pflaum^1,2, and Vladimir Dyakonov^1,2 — 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 (V_OC, J_SC, 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.