Formation of a photoactive quasi-2D formamidinium lead iodide perovskite in water

There has been no report on the synthesis of fluorescent α-phase stabilized quasi-2D FAPbI₃ [FA = CH(NH₂)₂] perovskite nanocrystals (NCs) in water. We report the top-down synthesis of fluorescent quasi-two dimensional (2D) α-FAPbI₃ NCs in aqueous media by controlling the electronic states of lead and the NCs size of FAPbI₃. The product was stable in ambient conditions for more than six months. We explored a detailed synthetic study, their emissive properties and phase stabilization mechanism corroborated by density functional theory (DFT) calculations. Single particle imaging and photoluminescence (PL) study of α-FAPbI₃ NCs bear the signature of dual emission, which indicates the formation of self-trapped excited states. Our findings will pave the way to develop phase-stabilized hybrid perovskite NCs in water, beneficial for optoelectronic devices.