High-Sensitivity Piezoelectric Tapping Sensors Based on (FAPbI3)0.85(MAPbBr3)0.15−PVDF Nanocomposite Films

Abstract High-performance (FAPbI3)0.85(MAPbBr3)0.15−PVDF (FMP) polymer nanocomposite films were fabricated by a facile drop-casting method, followed by thermal annealing at 120 °C for 2 h to promote crystallization and electroactive β-phase formation. Structural characterization by X-ray diffraction and ATR-FTIR confirmed enhanced crystallinity, with the FMP-25% v/v nanocomposite exhibiting the highest β-phase fraction of 82.19%. Field-emission scanning electron microscopy revealed uniform perovskite dispersion and improved interfacial compatibility, while piezoresponse force microscopy demonstrated enhanced electromechanical coupling for the nanocomposites with a maximum piezoelectric coefficient (d33) of 27.26 pm V−1. Ferroelectric polarization−electric field measurements at 500 and 1000 V (50 Hz) showed improved polarization behavior for the optimized nanocomposite. Broadband dielectric spectroscopy further revealed enhanced dielectric properties, whereas nanoindentation confirmed improved mechanical stability without compromising flexibility. The optimized FMP-25 % v/v device generated an open-circuit voltage of 56.35 V under manual hand tapping. Under a constant compressive load of 20 N, it produced peak-to-peak output voltages of 2.42 ± 0.25 V at 5 Hz and 2.86 ± 0.32 V at 10 Hz. Load-resistance measurements further established its high power-generation capability. Transmission electron microscopy, high-resolution TEM, and selected-area electron diffraction confirmed the highly crystalline perovskite phase and strong interfacial interactions with the PVDF matrix. Finally, the optimized nanocomposite functioned as a self-powered piezoelectric tapping sensor with excellent sensitivity, which can potentially be used for flexible, self-powered wearable sensors.