A Near-Room-Temperature Hybrid Organic–Inorganic Lead Halide Perovskite Ferroelectric [BrCH₂CH₂N(CH₃)₃][PbBr₃] and Its Flexible Composite Film

A hybrid organic–inorganic lead halide perovskite, [BrCH 2 CH 2 N(CH 3 ) 3 ][PbBr 3 ] ( BEPbBr ), obtained by matching a quasi-spherical (2-bromoethyl) trimethylammonium cation with an infinite one-dimensional zigzag [PbBr 3 ] − anion chain, exhibits a reversible ferroelectric phase transition at 302/286 K. Switchable dielectric and ferroelectricity were observed accompanied by the order–disorder phase transition at near-room-temperature. Further, the ferroelectric BEPbBr was dispersed into a PVDF matrix to form flexible BEPbBr@PVDF composite films. The β-phase PVDF content in composite films was significantly improved without requiring complicated after-treatment, and the ferroelectricity was also greatly enhanced resulting from the induced ordered orientation by the interactions between BEPbBr and β-phase dominated PVDF. This finding may promote research on near-room-temperature multifunctional switching smart materials and wearable devices by utilizing molecular ferroelectrics and their flexible films.