Phosphonium Cation-Based Ferroelectric 1D Halide Perovskite-Like Semiconductor for Mechanical Energy Harvesting

Organic-inorganic halide perovskites (OIHPs) have attracted tremendous attention from researchers because of their diverse applications in optoelectronics, sensing, catalysis, memory, photodetectors, and medical diagnostics. The presence of inherent ferroelectricity in these perovskite materials facilitates the separation of photogenerated electron-hole pairs. Here, we report a large phosphonium cation-based methyl triphenyl phosphonium lead bromide (MTPLB) perovskite-like semiconductor with a direct band gap of 3.49 eV, which shows ferroelectricity in both nanoscale and bulk at room temperature. The material exhibits a phase transition temperature of 477 K, a polarization saturation of 0.26 μC/cm², and a d₃₃ of 5.2 pC/N. MTPLB displays a robust piezoelectric response, as confirmed via advanced piezoresponse force microscopy (PFM). Further, we have fabricated nanogenerator devices with varying ratios of MTPLB and poly(vinylidene fluoride) (PVDF) composites for mechanical and biomechanical energy harvesting. We report an enhanced piezoresponse in all devices with the best response in the device with a 2% MTPLB loading in the PVDF matrix due to the triggering of the electroactive phases in PVDF. The improved output response, operational durability, and flexibility of the composite-based devices underscore their potential for advanced technological applications in electronics, actuators, sensors, and mechanical energy-harvesting processes.