Regensburg 2016 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 90: Poster III

HL 90.17: Poster

Thursday, March 10, 2016, 16:00–19:00, Poster A

Charge dynamics of Organometal Trihalide Perovskite using broadband transient absorption technique — •Yajun Gao¹, Tobias Schnier², Kestutis Budzinauskas¹, Jingyi Zhu¹, Selina Olthof², Klaus Meerholz², and Paul Loosdrecht¹ — ¹Physics Institute II, University of Cologne, Zülpicher street 77, 50937, Cologne, Germany — ²Physical Chemistry, University of Cologne, Luxemburger street 116, 50939, Cologne, Germany

Organometal trihalide perovskites provide a promising alternative for photovoltaic applications, with the highest solar cell power conversion efficiency of 19.3% as reported in 2014. The precise mechanism of power conversion in these materials is currently not well understood. In this work, we address this issue using visible and near-infrared broadband transient absorption (TA) spectroscopy, which can discriminate between free charges and excitons, to study the ultrafast charge generation in organometal trihalide perovskite CH3NH3PbI3 films. Charge selectivity is achieved by observing the transient response of charge-selective extraction layers, PCBM for electrons and spiro-OMeTAD for holes, spin-coated on the perovskite film. In addition to the response of the charge-selective layers, additional TA features show up which are attributed to free charges in the perovskite film. We use these experiments to determine the diffusion length of excitons and free carriers in the perovskite film, a property which is of central importance to the functionality of perovskite based solar cell devices.