Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 47: Organic Photovoltaics and Electronics I (joined session with CPP)
HL 47.2: Talk
Wednesday, March 22, 2017, 09:45–10:00, POT 81
Field-induced exciton separation in organic solar cells: Quantifying binding energies via luminescence quenching studies — •Marina Gerhard1, Andreas P. Arndt2, Uli Lemmer2,3, Ian A. Howard3, and Martin Koch4 — 1Department of Chemical Physics, Lund University, 22100 Lund, Sweden — 2Light Technology Institute, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany — 3Institute of Microstructure Technology, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen, Germany — 4Faculty of Physics and Materials Sciences Center, Philipps-Universität Marburg, 35032 Marburg, Germany
In this contribution we investigate the field- and temperature-dependence of luminescence quenching in organic solar cells (OSCs) employing a streak camera. We study the prototypical system PTB7:PC71BM, where different emissive species i.e. singlet and CT states can be identified by choosing appropriate excitation conditions.[1] The quenching behavior and PL dynamics are satisfactorily reproduced by a kinetic model based on exciton dissociation via a hopping mechanism,[2] allowing us to take the important influence of disorder into account. Moreover, our experimental and simulative approach suggests that the binding energy of the emissive CT state (ca. 50 meV) is about one order of magnitude below that of singlet states. The absence of strongly bound CT states acting as ’deep’ traps could essentially contribute to the high efficiency of the studied OSCs.
[1] M. Gerhard et al., J. Phys. Chem. C 119 (51), 2015, p. 28309
[2] O. Rubel et al., Phys. Rev. Lett. 100 (19), 2008, p. 196602