Low-Dimensional Single-Cation Formamidinium Lead Halide Perovskites (FA(m)(+2)Pb(m)Br(3)(m)(+2)): From Synthesis to Rewritable Phase-Change Memory Film

Abstract

Synthesis of 2D perovskites often demands long and bulky organic spacer cations, but they hamper optoelectronic properties of the resulting 2D perovskites. Novel low-dimensional single-cation perovskites with a general formula of FA(m)(+2)Pb(m)Br(3)(m)(+2) are prepared by using a quenching-assisted solution process, which leads to the wide dimensional control over 1D FA(3)PbBr(5) (m = 1), 2D FA(m)(+2)Pb(m)Br(3)(m)(+2) (m ˃= 2), and 3D FAPbX(3) (m = infinity) perovskites simply by changing the composition of precursors. In this case, formamidinium (FA) acts as both an A-site cation and spacer cation in FA(m)(+2)Pb(m)Br(3)(m)(+2). Unlike conventional 2D perovskites, FA(m)(+2)Pb(m)Br(3)(m)(+2) perovskites have (110) orientation. PVDF (poly(vinylidene fluoride)) preferentially stabilizes the low-dimensional FA(m)(+2)Pb(m)Br(3)(m)(+2) phases, which is utilized to fabricate the stable FA(m)(+2)Pb(m)Br(3)(m)(+2)-PVDF composite films. The phase transitions from 1D and 2D to 3D are investigated in response to various stimuli, including humidity, ultraviolet, oxygen, and solvents, are exploited for rewritable phase-change memory films.