Reversible and Irreversible Electric Field Induced Morphological and Interfacial Transformations of Hybrid Lead Iodide Perovskites.

We report reversible and irreversible strain effects and interfacial atomic mixing in MAPbI3/ITO under influence of external electric bias and photoillumination. Using conductive-probe atomic force microscopy, we locally applied a bias voltage between the MAPbI3/ITO and the conductive tip and observed local dynamic strain effects and current under conditions of forward bias. We found that the reversible part of the strain is associated with a current spike at the current onset stage and can therefore be related to an electrochemical process accompanied by local molar volume change. Similar partly reversible surface deformation was observed when the tip-sample contact was illuminated by light. Time-of-flight secondary ion mass spectrometry of electrically biased regions revealed massive atomic mixing at the buried MAPbI3/ITO interface, while the top MAPbI3 surface, subjected to strong morphological damage at the tip-surface contact, revealed less significant chemical decomposition.