Lead‐Free Hybrid Halide Perovskite for Piezoelectric Energy Harvesting

ABSTRACT Halide perovskites are widely recognized for their exceptional optoelectronic properties, cost‐effective fabrication, and tunable chemical compositions, which make them highly versatile in photovoltaics, LEDs, and mechanical energy harvesting. Here we have developed a novel manganese‐based lead‐free Benzyl trimethyl ammonium manganese bromide (BTMB) perovskite in the polar non‐centro symmetric space group P2 ₁ system, which shows strong piezoresponse properties measured using sophisticated Piezo Force Microscopy (PFM) and Switching Spectroscopy Piezo Force Microscopy (SS‐PFM). BTMB exhibits a direct bandgap of 4.3 eV along with a bright luminescence in the visible region due to ligand‐to‐metal charge transfer mechanism. The material demonstrates a polarization saturation value of 4.0 µC/cm ² with d ₃₃ value of 3.95 pC/N measured using quasi electrostatic d ₃₃ meter on a pellet of thickness 1.5 mm. PFM results show notable ±180 ⁰ phase changes upon application of bias with characteristic butterfly and hysteresis loop, a clear indication of reversal of polarization switching. Further, we have fabricated a mechanical energy‐harvesting device by incorporating BTMB into polydimethylsiloxane (PDMS) polymer matrix containing 30 weight percent of the material to achieve a peak output voltage of 1.1 V and a peak current density of 250 nA/cm ² with an achievable output power of ∼1.1 µW/cm ² at RT.