Unveiling the Synergistic Piezo-Phototronic Dynamics in Indium Selenide incorporated Poly(vinylidene fluoride) Nanocomposites for Next-Generation Energy Harvesting

Abstract

Piezo-phototronics leverages the synergy of piezoelectricity and photoexcitation to enable advanced optoelectronic functionalities in flexible materials and devices. In this study, we report for the first time, the fabrication and comprehensive evaluation of indium selenide (In 2 Se 3 ) incorporated poly(vinylidene fluoride) (PVDF) nanocomposites, designed to maximize piezo-phototronic performance through engineered strain-polarization induced optoelectronic coupling. The introduction of two-dimensional In 2 Se 3 nanofiller into the PVDF matrix led to a substantial increase in electroactive β and γ-phase content, with the optimized PVDF nanocomposite of 2 wt.% In 2 Se 3 (PVIS_2) achieving ~ 91% polar phase, a piezoelectric coefficient (d 33 value) of ~ 53.4 pm/V, and an output voltage of ~ 70.5 V. Enhanced energy conversion was further demonstrated by a power density of ~ 46.6 μW/cm 2 and current density of ~ 1.64 μA/cm 2 . UV-visible spectroscopy revealed strong absorption at 373 nm, derived from the In 2 Se 3 nanoparticles, which enables PVIS_2 photodetector film to generate reproducible and stable photocurrent with an on-off switching current of ~ 2.21 μA and UV photoresponsivity at a bandgap of ~ 3.3 eV. The device also exhibited a responsive piezophototronic effect, with output voltages of ~ 9.8 V under illumination and ~ 4.8 V in the dark, confirming dual sensitivity to light and mechanical stimuli. These results highlight PVIS_2 nanocomposite as promising candidate for next-generation, self-powered optoelectronic sensor capable of efficient multifunctional energy harvesting and environmental monitoring.