Enhanced piezo-response in copper halide perovskites based PVDF composite films

In-situ fabricated perovskite nanocrystals in polymeric matrix provide new generation composite materials for plenty of cutting edge technology. In this work, we report the in-situ fabrication of copper halide perovskite (MA₂CuCl₄, MA:CH₃NH₃ ⁺) embedded poly(vinylidene fluoride) (PVDF) composite films. The optimized MA₂CuCl₄/PVDF composite films exhibit greatly enhanced piezo-response in comparasion with pure PVDF films. The enhancements were invesitgated and explained by applying piezo-response force microscopy (PFM) measurements and density functional theory (DFT) caculations. We proposed that the high piezoelectric properties of MA₂CuCl₄/PVDF composite films could be related to the large Cu off-centering displacement, the strong interactions between MA₂CuCl₄ and PVDF as well as large stress concentration around the MA₂CuCl₄ particles in the films. These piezoelectric composite films are expected to be suitable functional materials for flexible and/or wearable piezoelectrics.