Berlin 2012 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 6: Poster: Structural Ordering and Electronic Transport (joint focus with HL)
CPP 6.8: Poster
Monday, March 26, 2012, 17:30–19:30, Poster A
Solvent additives for tuning the photovoltaic properties of polymer-fullerene solar cells — •Anna Göritz1, Antonietta De Sio2, Thomas Madena2, Ralph Huber2, Jürgen Parisi2, Shany Neyshtadt3, Felix Deschler3, Enrico Da Como3, Salvatore Esposito4, and Elizabeth von Hauff1,2 — 1Physics Institute, University of Freiburg — 2Physics Institute, University of Oldenburg — 3Dep. of Physics and CeNS, LMU, Munich — 4ENEA Research Center, Localita Granatello, Portici, Italy
We demonstrate that using solvent additives to prepare P3HT:PCBM blends increases the performance of bulk heterojunction solar cells by inducing favorable phase segregation and increased polymer ordering in the active layer[a]. The solvent additives 1,2,3,4-tetrahydronaphtalene (THN) and chlorobenzene were added to the host solvent 1,2-dichlorobenzene (oDCB) to influence the film formation properties. Solar cells prepared using solvent additives resulted in higher photocurrents than solar cells prepared using pure oDCB, and blends prepared from THN resulted in best efficiencies. Structural investigations with TEM, AFM, and Kelvin probe force microscopy indicated that the solvent additives lead to preferential in-plane phase segregation between the polymer and fullerene and increased P3HT ordering in the blends. The solvent additives led to a decrease in the PCBM content at the top of the blend, resulting in lower fill factor in the solar cells and reduced bulk electron transport. We discuss these results considering the effects of morphology on charge separation.
[a]A.De Sion et al., Solar Energy Materials a. Solar Cells 95/12(2011)