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

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 beta-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 x 1.2 cm effective contact area and 70 mu m 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 mu F capacitor and power small electronic devices such as a timer using 22 mu F. 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.