Coupling of interface effects and porous microstructures in translucent piezoelectric composites for enhanced energy harvesting and sensing

Abstract Piezoelectric polyvinylidene fluoride (PVDF) and its copolymer based piezoelectric nanogenerators (PENGs) have attracted extensive attention, which can hopefully be applied in the fields of wearable electric devices and sensing systems. However, one great challenge that limits their large-scale application is to achieve PVDF based composites with high piezoelectric performance. Herein, a facile and efficient method is proposed to develop translucent, porous composites with high β phase content and abundant micropores. Enhanced β phase formation is attributed to the electrostatic bonding between fillers (ZnO nanoparticles and Ag nanowires) and -CH2 and -CF2 chains, yet, local conformational disorder at the ZnO-matrix interface region caused by strong interface effect results in local stabilization of β phase. Coupling of high β phase content and microporous structure is believed to be essential for achieving considerable piezoelectric outputs (7.1 μW/cm2) and excellent force sensitivity (1.155 V/kPa). In practical applications, the composites based PENGs can efficiently harvest mechanical energy from human motions and detect weak physiological signals. Furthermore, a 3 × 2 pixel tactile sensor array is integrated successfully to work as self-powered flexible coded lock without power supply. Our work offers a simple approach to high-performance piezoelectric composites and moves a step toward sensing application.