Dresden 2014 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 29: Poster: Organic semiconductors and hybrid organic-inorganic heterostructures / Organic photovoltaics

HL 29.8: Poster

Montag, 31. März 2014, 17:00–20:00, P2

Effect of the donor-acceptor morphology on the recombination behavior in polymer-fullerene bulk heterojunction solar cells — •Sebastian Wilken, Michael Koopmeiners, Jürgen Parisi, and Holger Borchert — University of Oldenburg, Department of Physics, Energy and Semiconductor Research Laboratory, Carl-von-Ossietzky-Str. 9-11, 26129 Oldenburg, Germany

In this study, we discuss the impact of the donor-acceptor morphology on the recombination behavior in polymer-fullerene bulk heterojunction solar cells based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM). Different amounts of nanoscale phase separation have been obtained by using 1,2-dichlorobenzene and chlorobenzene as spin-casting solvents, respectively, as is visualized by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Both the current-voltage characteristics and the white-light bias external quantum efficiency with respect to varying illumination intensities suggest that the dominant recombination mechanism, i.e., monomolecular and bimolecular recombination, is strongly correlated with the respective nanomorphology of the P3HT:PCBM blend. To further evaluate the influence of charge carrier trapping, transient photocurrent measurements have been performed and analyzed in terms of emssion time constants τ_e,i, assuming that each τ_e,i is characteristic for one distinct trap level i. In addition, the temperature dependence of τ_e,i was investigated to gain information about the thermal activation energy Δ E_i of the corresponding emission process.