A self-powered mechanical energy harvester based on CH₃NH₃PbI₃ doped P(VDF-HFP)/PANI composite films

Piezoelectric polymers, particularly poly(vinylidene fluoride) (PVDF) and its copolymers attract attention from researchers due to their stretchability, flexibility, lightweight, and most importantly their biocompatible nature. In this research work, we report on the preparation of polymer composite films as flexible piezoelectric generators (PGs) and their electroactive phase (β- and γ-phase) formation. The piezoelectric properties of copolymer poly(vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP)) have been enhanced by incorporating polyaniline (PANI) and methylammonium lead iodide (CH₃NH₃PbI₃) into it for a higher yield of the electroactive phases where a traditional electrical poling treatment was avoided. The remarkable enhancement in the piezoelectric phase (i.e., β-phase) of the P(VDF-HFP) copolymer has been reported in this work, and it is found that the overall improvement of the piezoelectric β-phase and the conversion of the degree of crystallinity is governed by the incorporation of the PANI and CH₃NH₃PbI₃ fillers as revealed by the attenuated total reflectance (ATR) and X-ray diffraction (XRD) analysis. The X-ray photoelectron spectroscopy (XPS) analysis further confirmed the interfacial dipole-dipole interaction of PANI with the P(VDF-HFP) copolymer matrix. Piezoelectric generators (PGs) fabricated from the composite films show an open circuit piezoelectric voltage output of 5 volts and an output power of 8.2 nW. The capacitor charging capability by simple repetitive finger touch and release motions (a pressure amplitude of ∼14 kPa) of the flexible PGs promises their applicability as a piezoelectric-based energy harvester where different mechanical vibrations can be utilized.