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Ferroelectric Poling of Methylammonium Lead Iodide Thin Films
Author(s) -
Röhm Holger,
Leonhard Tobias,
Hoffmann Michael J.,
Colsmann Alexander
Publication year - 2020
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201908657
Subject(s) - poling , piezoresponse force microscopy , ferroelectricity , materials science , electric field , polarization (electrochemistry) , pyroelectricity , thin film , piezoelectricity , optoelectronics , perovskite (structure) , electrode , semiconductor , nanotechnology , condensed matter physics , dielectric , crystallography , composite material , chemistry , physics , quantum mechanics
Seemingly contradictory reports on polar domains and their origin have surrounded the controversial discussion about the ferroelectricity of the methyl ammonium lead iodide (MAPbI 3 ) thin films that are commonly employed in perovskite solar cells. In this work, microscopic modulations of the polar domain patterns upon application of an electric poling field are correlated with macroscopic changes to the currents through the MAPbI 3 layer. Piezoresponse force microscopy is used to monitor the widening, narrowing, generation or extinction of polar domains, as well as shifts of the domain walls at room temperature under an in‐plane electric poling field that is applied between two laterally organized electrodes. This poling leads to a net polarization of individual grains and the thin film itself. Macroscopically, this net polarization results in a persistent shift of the diode characteristics that is measured across the channel between the electrodes. Both the modulation of the polar domains upon electric poling and the concurrent persistent shift of the electric currents through the device are the unambiguous hallmarks of ferroelectricity, which demonstrate that MAPbI 3 is a ferroelectric semiconductor.