Regensburg 2019 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 2: Hybrid and Perovskite Photovoltaics I
CPP 2.6: Vortrag
Montag, 1. April 2019, 11:00–11:15, H18
Interfacial Characteristics and Charge Carrier Dynamics in Formamidinium Tin Iodide and Phenylethylammonium/Formamidinium Tin Iodide — •Jonas Horn1, Mirko Scholz2, Kawon Oum2, Thomas Lenzer2, and Derck Schlettwein1 — 1Justus-Liebig-Universität Gießen, Institut für Angewandte Physik — 2Universität Siegen, Physikalische Chemie
Electrical and optical measurements were performed at formamidinium tin iodide (FASnI3) and its phenylethylammonium (PEA) derivative PEA0.08FA0.92SnI3, representing attractive alternatives to lead-based perovskites. Charge transport across metal-perovskite interfaces and through the perovskite films were studied on microstructured gold electrode arrays. Hysteresis in the current-voltage characteristics and a corresponding current-time behavior indicated limitation by interfacial charge transfer. Smaller persistent changes following prolonged polarization was measured in PEA0.08FA0.92SnI3 compared to FASnI3 which is explained by a 2-dimensional interlayer at the contacts leading to decreased field-induced migration of ions. The rate constants for the Auger- and bimolecular recombination processes were obtained from femtosecond transient absorption experiments. A time constant of 0.5 ps was found for the scattering of charge carriers by optical phonons, even faster than measured in lead-based perovskites. Carrier recombination in the bulk material was not substantially influenced by the substitution of FA by PEA. Changes in the electrical characteristics of PEA0.08FA0.92SnI3 compared to FASnI3 are, therefore, assigned to different contact rather than bulk characteristics.