Extra Polarization-Engineered Power Generation of CNT/Halide Composite Nanofibers

Diverse nanostructures have been widely applied for efficient energy generation in low-power consuming and self-powering devices. Herein, we explore the origin of bending-driven power generation in carbon nanotube (CNT)/halide/poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) nanofiber and their versatile applications in piezoelectric energy harvester, tactile sensor, and pressure sensor. Two effective fillers of inorganic halide perovskite CsPbBr₃ nanocrystals and CNT were incorporated in P(VDF-TrFE) matrix to demonstrate bending-driven energy harvesting performances and their ability to sense physiological signals from the human motions. Owing to the synergistic piezoelectric coupling between the fillers and the matrix, impressive harvesting outputs of ~15.9 V and 1,128 nA were achieved for the 0.3 wt.% CNT and 5 wt.% halide-incorporated samples, which are ~17.6 and 10.5 times better than the results achieved for the pure P(VDF-TrFE) nanofiber harvester. The values are also the best values reported using bending-driven operations. The origin of substantial enhancements in electromechanical energy generation under the bending motions is attributed to the extra dipolar polarization by embedded CsPbBr₃ and space-charge polarization by dispersed CNTs in contact with the piezoelectric polymer matrix. Wearable physiological and pressure sensors were successfully demonstrated to effectively sense the motions and convert them into electric signals. The optimal nanofiber sensors demonstrated a wide force detection range from 0.002N to 600 N, and superior reliability and repeatability for 20,000 cycles under the periodic mechanical deformation. Nanofiber composites-based pressure sensor was further applied in the pressure signal-mapping system, demonstrating its promising possibility in the self-powered health monitoring system.