Enhanced nanogenerator by embedding lead-free double perovskite Cs2AgBiBr6 in polymer matrix for hybrid energy harvesting

Abstract

Mechanical energy harvesters fabricated with halide perovskites display excellent electrical output because of their prominent permittivity. An all-inorganic lead-free double perovskite, Cs₂AgBiBr₆ (CABB), with competitive performance, excellent environmental stability and non-toxicity can break the confines of practical unavailability. CABB microcrystals, which are effective nucleating agents and dielectric fillers, are embedded into a polyvinylidene-fluoride (PVDF)-matrix as efficient electron-acceptors to induce electro-active PVDF β-phase formation and enhance the composite dielectric constant, which contributes to notable hybrid electric outputs. CABB–PVDF hybrid nanogenerators with the optimal CABB concentration of 20 wt% possess triboelectric and piezoelectric effects, with a nanogenerator with a 1.2 cm × 1.2 cm effective contact area and 70 μm film thickness exhibiting a unique response with an open-circuit voltage of 126 V and a short-current density of 4.67 mA m⁻² under a 0.5 Hz mechanical frequency and 4 cm s⁻¹ motion speed. An identical device achieves the highest output power density of 0.39 W m⁻² at 8 Hz and 0.64 m s⁻¹, which could light up at least 86 commercial LEDs using a 1 μF capacitor and power small electronic devices such as a timer using 22 μF. The corresponding force sensing is achieved with a different distribution of external forces using a 10 wt% CABB–PVDF composite film. This functional composite maintains its stability and charge retention capacity for effective application in various environmental conditions.