Halide-Tunable Bond Engineering for High-Performance Multi-Responsive Piezoelectric Sensors via Enhanced...

Developing piezoelectric materials with substantial strain output and large voltage constant, alongside superior piezoelectric performance and mechanical softness remains a long-standing challenge for promising practical applications. Herein, an in-situ fabrication strategy is demonstrated to resolve these obstacles by engineering molecular bond angle/length and simultaneously improving electrostatic polarization domain in self-aligned halide perovskite nanorods (NRs) embedded polyvinylidene fluoride (PVDF) nanofibers (NFs). Introducing large-size iodine into CsPbBr₃ crystals weakens metal-halide bonds in CsPbI₂Br, softening bond strength and enhancing electrostatic polarization in PVDF. The optimized CsPbI₂Br/PVDF NFs membrane achieves exceptional piezoelectric performance, with a high piezoelectric coefficient (d₃₃) of 67.5 pC N^-1 and a piezoelectric figure of merit of 10.7 × 10^-12 m² N^-1, representing 562% and 443% enhancements over the pure PVDF NFs membrane, respectively. Simultaneously, it offers superior mechanical softness, exhibiting a Young's modulus of ≈208 MPa and a strain up to 91.5%. Density functional theory is employed to predict the halide-tunable latice distortion, which is responsible for the enhanced piezoelectricity. Furthermore, the fabricated sensor demonstrates excellent stability (≈10 000 cycles), detects  various mechanical deformations, and powers multiple commercial LEDs through simple daily human activities, highlighting its strong potential as a high-performance, portable, and wearable energy harvesting device.