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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: P3: Hybrid Photovoltaics and Preovskites

CPP 31.8: Poster

Dienstag, 17. März 2015, 14:00–16:00, Poster B

Recombination Dynamics in Perovskite Solar Cells probed by Time-Delayed-Collection-Field (TDCF) Experiments — •Andreas Paulke¹, Samuel D. Stranks², Henry J. Snaith², Dieter Neher¹, and Thomas J.K. Brenner¹ — ¹Institute of Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str.24-25, D-14476 Potsdam-Golm, Germany — ²Department of Physics, University of Oxford, Clarendon Laboratory, Parks Road, Oxford OX1 3PU, United Kingdom

Time-Delayed-Collection-Field (TDCF) experiments are applied to working perovskite (CH₃NH₃PbI_3−xCl_x) solar cells with different device architectures. In TDCF, charges generated by a nanosecond optical pulse are extracted by a large reverse voltage pulse. Thereby, the delay between the photoexcitation and the extraction is tuned over a wide range, with a minimal delay of 10ns. This allows to probe the temporal evolution of the photogenerated charges and quantify nongeminate recombination losses in the device. For comparison, the charge carrier dynamics of an all-organic device (PTB7:PC71BM) with similar performance is studied under comparable illumination conditions. We find that the predominant recombination mechanism in perovskite solar cells is very different from that of the organic cell. In particular, while the charge carrier dynamics in the all-organic cell can be described by purely bimolecular recombination with a time and fluence independent BMR coefficient, the dynamics in mesoporous-TiO₂/Perovskite/Spiro and planar PEDOT:PSS/Perovskite/PCBM devices is characterized by a slow-down of the recombination rate over several microseconds.