Dresden 2017 – wissenschaftliches Programm
CPP 13.21: Poster
Montag, 20. März 2017, 18:30–21:00, P1A
Photoinduced Charge Generation and Dynamics in Mixed Formamidinium Methylammonium Lead Halide Perovskite Thin Films as Observed by fs Transient Absorption Spectroscopy — •Jonas Horn1,2,3, Iulia Minda2, Heinrich Schwoerer2, and Derck Schlettwein1,3 — 1Justus-Liebig-University Giessen, Institute of Applied Physics — 2Stellenbosch University, Laser Research Institute, South Africa — 3Justus-Liebig-University Giessen, Laboratory for Materials Science
Hybrid organic inorganic perovskite materials, in particular FA1−xMAxPbI3−yBry using formamidinium and methylammonium cations, are of great interest not only due to the rapid increase in power conversion efficiencies when applied in photovoltaic devices but also due to their astonishing optoelectronic properties. By means of transient absorption spectroscopy in the visible and near infrared spectral regions, temporal evolution of the population and depopulation of various electronic states and their associated spectral signatures was monitored. The detailed interpretation of the results leads to a consistent charge dynamic model of the initial photo-processes. Upon photoexcitation with 3.2 eV photon energy, hot electrons and holes are generated in the lowest conduction band and second highest valence band and relax to the band edges with a time constant of approximately 500 fs. Subsequently recombination, occurring on gradually faster time scales for hot versus cold electrons was shown and assigned to Auger- and bimolecular recombination.