Lead-Free Hybrid Halide Perovskite for Piezoelectric Energy Harvesting

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 P2₁ 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/cm² with d₃₃ value of 3.95 pC/N measured using quasi electrostatic d₃₃ meter on a pellet of thickness 1.5 mm. PFM results show notable ±180⁰ 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/cm² with an achievable output power of ∼1.1 µW/cm² at RT.