Transformation of Cs_3Bi_2Br_9 to Cs_2AgBiBr_6 Lead-Free Perovskite Microcrystals Through Cation Exchange

摘要

All-inorganic lead-free Cs_2AgBiBr_6 double perovskites have gained significantattention due to their potential as stable and nontoxic photoactivesemiconductors. Currently, it remains challenging to synthesizehomogeneous microcrystals (MCs) exhibiting excellent properties, which arenecessary for large-area device integration. This work proposes a two-stepsynthesis approach involving the introduction of a foreign silver cation totransform the 0D layered Cs_3Bi2Br_9 to 3D Cs_2AgBiBr_6 perovskite structure.This work has studied the cation exchange (CE) transformation mechanism byisolating intermediates to be able to follow the evolution of the crystal latticeas well as the structural and optical properties over time. Moreover, completeCE results in phase-pure, highly crystalline Cs_2AgBiBr_6 MCs exhibitingexcellent photonic properties, superior to their counterparts synthesized byanti-solvent precipitation. These findings highlight the potential of CE-inducedtransformation as a means of synthesizing novel, stable perovskites.