Understanding instability in formamidinium lead halide perovskites: kinetics of transformative reactions at grain and sub-grain boundaries
Résumé
Transformative and reconstructive reactions impart significant structural changes at particle boundaries of hybrid perovskites, which influence environmental stability and optoelectronic properties of these materials. Here, we investigate the moisture-induced transformative reactions in formamidinium based perovskites FAPbX3 (X=I, Br) and show that the ambient stability of these materials can be adjusted from a few hours to several months. For FAPbI3, roles of water vapor, particle size, and light illumination on the kinetic pathways of the cubic () transformation to the hexagonal () phase are analyzed by X-ray diffraction, optical microscopy, photoluminescence and solid-state NMR spectroscopy techniques. The grain and sub-grain boundaries exhibit different →-FAPbI3 phase transformation kinetics. Our study suggests that the dynamic transformation involves the local water-induced dissolution of the cubic phase
Domaines
Chimie
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nz-2022-00140b_Raval et al_Phase transitions in FAPbX3_manuscript_final.pdf (1.1 Mo)
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nz-2022-00140b_Raval et al_Phase transitions in FAPbX3_supp info_final.pdf (2.65 Mo)
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