Piezoelectricity in a mixture of chiral 1D hybrid lead bromide and iodide systems

Abstract

Chiral organic–inorganic hybrid perovskites possess inherent structural asymmetry and lattice flexibility, enabling a piezoelectric response suitable for energy harvesting and sensing technologies. Here, we introduced a new strategy for the development of a piezoelectric nanogenerator (PENG) constructed from a mixture of two chiral one-dimensional hybrid lead halides, (R-MBA)PbBr₃ and (R-MBA)PbI₃ (MBA: methylbenzylammonium). Individually, both hybrid halide systems exhibit piezoelectric behaviour, but when mixed, the piezoelectric output increases significantly. The highest performance is achieved for the optimized mixed halide mixture [75 wt% (R-MBA)PbBr₃ + 25 wt% (R-MBA)PbI₃]. To improve flexibility and mechanical endurance, we incorporated the optimized halide mixture into a polycaprolactone (PCL) polymer matrix. The device with 15 wt% of the optimized halide mixture embedded in PCL demonstrates the highest peak-to-peak voltage of 40.8 V with a power density of 83.1 μW cm^-2. The halide mixture–PCL composite significantly enhances the device performance, facilitated by its endurance to a higher impact force of 21 N at 8 Hz compared to the neat mixture of hybrid halide salts without PCL (4 N at 6 Hz), leading to a 1.5 times enhancement in the peak-to-peak voltage. Finally, self-powered pressure sensors were fabricated by integrating multiple PENG devices and demonstrated for smart door mat applications. These findings show that physical mixing of chiral hybrid lead halides might be a useful approach to enhance piezoelectric performance.