Dresden 2014 – scientific programme
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O: Fachverband Oberflächenphysik
O 32: Organic Semiconductors: Photovoltaics (HL jointly with CPP, DS, O)
O 32.9: Talk
Tuesday, April 1, 2014, 12:15–12:30, POT 081
The influence of fullerene loading on the photogeneration in intercalated polymer: fullerene bulk heterojunction solar cells — •Andreas Zusan1, Koen Vandewal2, Benedikt Allendorf1, Nis Hauke Hansen1, Jens Pflaum1, Martin Heeney3, Alberto Salleo2, Vladimir Dyakonov1,4, and Carsten Deibel1 — 1Experimental Physics VI, Julius-Maximilians-University of Würzburg, D-97074 Würzburg — 2Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA — 3Department of Chemistry, Imperial College, London, SW7 2AZ, UK — 4Bavarian Centre for Applied Energy Research e.V. (ZAE Bayern), D-97074 Würzburg
The conjugated polymer, pBTTT, allows a systematic tuning of the blend morphology by varying the acceptor material and blend ratio, making it a well-suited structural model for studying the fundamental processes in organic BHJ solar cells. To analyze the correlation between photogeneration and intercalation, we have performed time delayed collection field (TDCF) measurements and Fourier-transform photocurrent spectroscopy (FTPS) on pBTTT:PCBM devices in various stoichiometries. An increased PCBM loading resulted in a less field dependent dissociation, which we attribute to enhanced electron delocalization along extended PCBM nanophases and energetically driven spatial separation of polarons due to the presence of pure acceptor domains. The highly efficient transfer of charge carriers from the intercalated phase into the pure phase has been studied further by extending TDCF measurements to include segregated pBTTT:bisPCBM blends.