A Highly Electrostrictive A2BX4‑Type Hybrid 2D Perovskite Ferroelectric and the Utility of Its Piezoelectric Nanogenerator in Wireless Mat-Sensor Technology

The quasi-spherical theory and ligand halogenation have emerged as effective strategies for promoting polar noncentrosymmetric structures with potential ferroelectric properties. Here, we report a novel two-dimensional (2D) hybrid organic–inorganic perovskite, [p-ClBnNH3]2CdBr4, in the polar orthorhombic Ccc2 space group. The structural noncentrosymmetry was confirmed via second harmonic generation (SHG) measurements. Polarization-electric field (P–E) hysteresis measurements revealed a saturation polarization (Ps) of 1.28 μC cm–2 at room temperature. Furthermore, it exhibits a high electrostrictive coefficient (Q33) of 3.6 m4 C–2, surpassing those observed in traditional ferroelectrics. For energy harvesting applications, composite films were fabricated by embedding [p-ClBnNH3]2CdBr4 in thermoplastic polyurethane (TPU) matrix. The 10 wt % device yielded a piezoelectric nanogenerator (PENG) output voltage of 20.0 V and a power density of 67.6 μW cm–2. A prototype “mat-sensor”, which is a scalable smart force sensor, was developed, demonstrating rapid response and wireless functionality for real-time applications, including security systems.