Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 46: Poster Session IV

CPP 46.1: Poster

Mittwoch, 14. März 2018, 11:00–13:00, Poster A

Control of Charge-Carrier Concentration in Lead-Free Perovskite Thin Films Consisting of Formamidinium Tin Iodide — •Pascal Schweitzer, Jonas Horn, Raffael Ruess, and Derck Schlettwein — IAP, JLU Giessen, Germany

As a promising substitute material for toxic lead perovskites we investigated formamidinium tin iodide. Thin films were prepared by spin-coating in a one-step approach. The crystal structure was confirmed by XRD, the microstructure of the films was studied by SEM and the optical absorption characteristics (Burstein-Moss-shift) were investigated by UV-vis spectroscopy. To discuss optoelectronic applications of such films, understanding of the electronic characteristics is essential. Different measurement geometries and contact materials were tested in order to provide reliable electrical studies. Inert contact materials and symmetrical electrodes were used to concentrate on perovskite materials properties rather than the influence of additional hole- and electron transport layers in typical device structure. To avoid severely high charge carrier concentrations caused by self-doping, this was limited by intentional mixing with tin fluoride to compensate tin vacancies. Current-voltage-characteristics served to discuss hysteresis in the materials which led to insight into polarization effects that are crucial, e.g. for perovskite solar cells under working conditions. We applied impedance spectroscopy to Schottky-type contacts to follow the space charge capacity under potential variation. Thereby we determined the charge carrier concentration in dependence of permittivity via Mott-Schottky analysis.