Anisotropic δ-to-α Phase Transition in Formamidinium Lead Iodide Thin Films.

ABSTRACT: Thermal annealing on hybrid perovskites is essential to prepare high-quality solar cells with extraordinary efficiency, whose benefits include transformation of inactive phases such as δ-FAPbI₃ to active α-FAPbI₃. The detailed mechanism for such critical phase transition, however, has not yet been adequately studied. Here, we present multiscale microscopic observation to unravel the anisotropic δ-to-α transition in epitaxial FAPbI₃ thin films. We adopt polarized light microscopy that offers enhanced contrast to distinguish isotropic α-FAPbI₃ from the anisotropic δ-FAPbI₃. Facilitated by in situ heating, it allows us to identify heterogeneous nucleation of α-FAPbI₃ and the subsequent diffusional phase transition preferentiall

SUBMITTER: Yang C 

PROVIDER: S-EPMC11912570 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature