Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 72: Hybrid and Perovskite Photovoltaics I

CPP 72.3: Vortrag

Donnerstag, 15. März 2018, 15:45–16:00, C 264

Capacitance profiling of planar perovskite solar cells taking mobile charged defects into account — •Mathias Fischer¹, Kristofer Tvingstedt¹, Vladimir Dyakonov^1,2, and Andreas Baumann² — ¹Experimental Physics VI, Julius Maximilian University of Würzburg, 97074 Würzburg — ²Bavarian Center for Applied Energy Research (ZAE Bayern), 97074 Würzburg

Currently, numerous approaches are being pursued to generate intentionally doped hybrid perovskite semiconducting materials. The Mott-Schottky analysis is a standard method to determine the doping concentration and the built-in potential. It is based on the fact that the depletion layer thickness, and therefore the capacitance changes with an applied electric field. In perovskite solar cells, however, this is typically not the case. We show experimentally that mobile charged defects might lead to erroneous values when not being considered. Instead, charges accumulated at the interface between the perovskite and a transport layer lead to an inhomogeneous doping distribution which is reflected in an underestimated built-in potential and doping density. We present electrical impedance measurements on planar solution-processed methylammonium and formamidinium lead iodide solar cells in a p-i-n configuration. Thereby, we derived a new measurement routine to determine the depletion layer capacitance as well as the doping density and the built-in potential by means of Mott-Schottky analysis. Finally, we provide informations on intentional or unintentional doping profiles in these solar cells.