Enhanced electromechanical conversion via in situ grown CsPbBr₃ nanoparticle/poly(vinylidene fluoride) fiber composites for physiological signal monitoring

Mechanical energy conversion based on the piezoelectric principle has received significant attention due to its promising applications in sustainable power supply systems and sensor technology. Ferroelectric poly(vinylidene fluoride) (PVDF) combines the advantages of both good electromechanical coupling and easy processability, yet its low piezoelectric coefficient limits its output performance and it thus cannot meet the increasing requirements for power generation and sensing. Here, inorganic metal halide perovskite CsPbBr₃ (CPB) nanoparticles are incorporated into PVDF fibers via an electrospinning technique, where an in situ crystallization and growth process of the CPB nanoparticles is established. Both the CPB nanoparticles and PVDF fibers are poled by the electric field during the electrospinning process, which promotes the formation of the polar phase of PVDF and distortion of the CPB lattice, resulting in greatly enhanced piezoelectric performance for the CPB/PVDF composites. The output performance under the external force of a flexible generator developed from electrospun CPB/PVDF films is significantly enhanced compared with the neat PVDF film, with an 8.4 times higher maximum open circuit voltage value. Furthermore, the measurements on the microscopic piezoelectric responses unambiguously reveal that the increased polar phase mainly contributes to the enhanced electromechanical coupling. The functions of the CPB/PVDF films as physiological signal monitoring sensors are determined and they demonstrate their potential applications as flexible piezoelectric generators and electronics for wearable health monitoring.