Phase Transition Kinetics of MAPbI₃ for Tetragonal-to-Orthorhombic Evolution.

ABSTRACT: Despite the commonly observed phase-instability-induced photovoltaic degradation of MAPbI₃, the phase transition kinetics at the atomic level remains elusive. Herein, by developing a stepwise NEB method, we clarify a nonsynergistic minimum-energy pathway for the tetragonal-to-orthorhombic phase transition. It is kinetically driven by the tilting of PbI₆ ^4- that induces a spontaneous small rotation of adjoining MA⁺ and ends with stepwise ∼110° reorientations of two nonadjacent MA⁺ enabled by the cavity expansion. Compared to the common concerted mechanism, this process gives a low barrier of 0.08 eV/unit, demonstrating the easiness of the transition at extremely low temperatures and the importance of rotational entropies in regulating t

SUBMITTER: Wu J 

PROVIDER: S-EPMC10131189 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature