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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur
KFM 4: Perovskite and photovoltaics I (joint session HL/KFM)
KFM 4.6: Talk
Monday, March 18, 2024, 10:45–11:00, EW 203
Changes in Polarization Mechanisms Following Dimensional Reduction of the Double Perovskite Octahedral Network in Cs2AgBiBr6 — •Tim P. Schneider, Jonas Glaser, Jonas Horn, and Derck Schlettwein — Institut für Angewandte Physik, Justus-Liebig-Universität Gießen
Introduction of large organic cations into metal halide perovskites leads to dimensional reduction of the octahedral metal-halide network towards so-called 2D-perovskites with significant changes in the electronic system. Such 2D-perovskites are recently studied to enhance the performance of perovskite solar cells by reducing hysteretic behavior and improving the contact formation of perovskite absorbing layers to transport layers. In this work, 2D PEA4AgBiBr8 is derived from its 3D counterpart Cs2AgBiBr6 by replacing Cs+ by the large organic phenethylammonium (PEA+) cation. Thin films of both materials, 3D Cs2AgBiBr6 or 2D PEA4AgBiBr8, were prepared onto microstructured metal electrode arrays to perform I-U measurements and spatially resolved Kelvin probe force microscopy. These experiments serve to characterize the contact formation of both materials and discuss hysteresis caused by ion migration in response to an applied electric field. It was revealed how the dimensional reduction of the octahedral network affects the polarization caused by ionic movements and the formation of contact resistances in the films and at the respective interface to the metal electrodes. Differences among the materials, implications for technical applications in devices and the respective origin of the different observed polarization phenomena will be discussed.
Keywords: interface; 2D perovskite; hysteresis; ion migration; Kelvin probe