Piezoelectric scattering limited mobility of hybrid organic-inorganic perovskites CH₃NH₃PbI₃

Carrier mobility is one of the most important parameters for semiconducting materials and their use in optoelectronic devices. Here we report a systematic first principles analysis of the acoustic phonon scattering mechanism that limits the mobility of CH₃NH₃PbI₃ (MAPbI₃) perovskites. Due to the unique hybrid organic-inorganic structure, the mechanical, electronic and transport properties are dominated by the same factor, i.e. the weak interatomic bond and the easy rotation of methylammonium (MA) molecules under strain. Both factors make MAPbI₃ soft. Rotation of MA molecule induces a transverse shift between Pb and I atoms, resulting in a very low deformation potential and a strong piezoelectricity in MAPbI₃. Hence the carrier mobility of pristine MAPbI₃ is limited by the piezoelectric scattering, which is consistent to the form of its temperature dependence. Our calculations suggest that in the pristine limit, a high mobility of about several thousand cm² V^-1 S^-1 is expected for MAPbI₃.