All‐Electrospun, Water‐Resistant, Breathable, Wearable, and Stable Metal Halide Perovskite Engineered Electroactive Polymer Textiles for Flexible Piezoelectric Nanogenerator

Abstract Halide perovskite materials have recently received a lot of attention in the field of optoelectronic and energy harvesting applications regardless of their environmental instabilities. Herein, a three‐layer assembled wearable piezoelectric nanogenerator (PENG) is fabricated by continuous electrospinning process, where the middle layer is an active component, made of Cs 3 Bi 2 I 9 ‐PVDF (PVDF‐CBI) nanofiber and outer layers are conducting ( σ ≈ 2.2 S m −1 ) electrodes of PEDOT‐coated PVDF (PVDF‐PEDOT) nanofiber mats. The incorporation of perovskite Cs 3 Bi 2 I 9 fillers fully induces β ‐phase (i.e., 100% of yield) in the PVDF matrix. Furthermore, the mechanism of electroactive β ‐phase formation is analyzed by DFT studies. The PENG is able to generate superior open circuit voltage of ≈12 V, short circuit current of ≈7 µA, and power density of 3 µW cm −2 . In addition, it demonstrates remarkable breathability (b ≈1.13 kg m −2 d −1 ), flexibility, water‐resistive properties (water contact angle ≈138 ◦ ), and mechanoacoustic sensitivity (S m ≈5 V Pa −1 ), enabling the development of robust wearable devices that are efficient enough to monitor human physiological motions and simultaneously harvest the biomechanical energy. These findings ingeniously promote the acceptability of lead‐free metal halide perovskite and conducting polymer in wearable energy harvesting, self‐powered robotics, and health‐care devices applications.