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Iodide-methylammonium interaction is responsible for ferroelectricity in CH3NH3PbI3

DOI: 10.1002/anie.201910599 DOI Help

Authors: Joachim Breternitz (Helmholtz-Zentrum Berlin für Materialien und Energie) , Frederike Lehmann (Helmholtz-Zentrum Berlin für Materialien und Energie) , Sarah A. Barnett (Diamond Light Source) , Harriott Nowell (Diamond Light Source) , Susan Schorr (Freie Universität Berlin)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Angewandte Chemie International Edition

State: Published (Approved)
Published: October 2019
Diamond Proposal Number(s): 17170

Abstract: Excellent conversion efficiencies of over 20% and facile cell production have placed hybrid perovskites at the forefront of novel solar cell materials with CH3NH3PbI3 being its archetypal compound. The question why CH3NH3PbI3 has such extraordinary characteristics, particularly a very efficient power conversion from absorbed light to electrical power, is hotly debated with ferroelectricity being a promising candidate. This does, however, afford the crystal structure to be non‐centrosymmetric and we herein present crystallographic evidence as to how the symmetry breaking occurs on a crystallographic, and therefore long‐scale, level. While the molecular cation CH3NH3+ is intrinsically polar, it is heavily disordered and cannot be the sole reason for ferroelectricity. We show that it, nonetheless, plays an important role as it distorts the neighbouring iodide positions from their centrosymmetric positions.

Journal Keywords: structure elucidation; Photovoltaic Materials; Inorganic Chemistry; hybrid perovskites; Ferroelectricity

Subject Areas: Chemistry, Materials


Instruments: I19-Small Molecule Single Crystal Diffraction