Rotational Dynamics of Organic Cations in Formamidinium Lead Iodide Perovskites.

ABSTRACT: We report results from quasi-elastic neutron scattering studies on the rotational dynamics of formamidinium (HC[NH₂]₂⁺, FA) and methylammonium (CH₃NH₃⁺, MA) cations in FA_1-xMA_xPbI₃ with x = 0 and 0.4 and compare it to the dynamics in MAPbI₃. For FAPbI₃, the FA cation dynamics evolve from nearly isotropic rotations in the high-temperature (T > 285 K) cubic phase through reorientations between preferred orientations in the intermediate-temperature tetragonal phase (140 K < T ⩽ 285 K) to an even more complex dynamics, due to a disordered arrangement of the FA cations, in the low-temperature tetragonal phase (T ⩽ 140 K). For FA₀

SUBMITTER: Laven R 

PROVIDER: S-EPMC10041645 | biostudies-literature | 2023 Mar

REPOSITORIES: biostudies-literature