Dresden 2017 – scientific programme
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DS: Fachverband Dünne Schichten
DS 5: Fundamentals of Perovskite Photovoltaics I (jointly with CPP)
DS 5.5: Talk
Monday, March 20, 2017, 11:45–12:00, ZEU 222
Local Time-Dependent Charging in a Perovskite Solar Cell — Victor W. Bergmann1, Ilka M. Hermes1, Dan Li1, Alexander Klasen1, Simon Bretschneider1, Eiichi Nakamura2, Rüdiger Berger1, and •Stefan A.L. Weber1,3 — 1Max Planck Institute for Polymer Research, 55128 Mainz, Germany — 2The University of Tokyo, Tokyo 113-0033, Japan — 3Johannes Gutenberg University Mainz, 55128 Mainz, Germany
Efficient charge extraction within solar cells explicitly depends on the optimization of the internal interfaces. Potential barriers, unbalanced charge extraction or interfacial trap states can prevent cells from reaching high power conversion efficiencies. Furthermore, in perovskite solar cells, slow processes happening on timescales of seconds cause hysteresis. Here, we report on local and time-dependent potential measurements with Kelvin probe force microscopy (KPFM) on cross sections [1] of planar methylammonium lead iodide (MAPI) perovskite solar cells. The KPFM revealed distinct differences in the charging dynamics at interfaces of the MAPI to adjacent layers [2]. Illumination experiments showed that more than one process is involved in hysteresis. By locally resolving these processes we found distinct differences in the charging dynamics in different regions of the device. Our results support the scenario of mobile ions and interfacial trap states for explaining the hysteresis in our device. [1] Nat. Commun. 2014, 5. [2] ACS Appl. Mater. Interfaces, 2016, 8 (30), 19402.