Self-poled P(VDF-TrFE)/Carbon Black Thin Film: A Cost-Effective Approach to Enhance Piezoelectric Nanogenerator for Wearable Sensing

Abstract Poly(vinylidene fluoride–trifluoroethylene) [P(VDF-TrFE)] is a promising ferroelectric polymer for energy harvesting and wearable sensing applications owing to its high piezoelectricity, flexibility, and biocompatibility. However, conventional P(VDF-TrFE) films require electrical or thermal poling to align dipoles and achieve strong piezoelectric output, which increases processing cost and complexity. In this work, we demonstrate a simple and cost-effective approach to realizing self-poled P(VDF-TrFE) films by incorporating carbon black (CB) nanofillers. Composite films containing 0–0.6 wt.% CB were fabricated on flexible indium tin oxide (ITO)/polyethylene terephthalate (PET) substrates and systematically characterized by x-ray diffraction (XRD) analysis, Fourier-transform infrared (FTIR) spectroscopy, optical microscopy, and atomic force microscopy (AFM). Both XRD analysis and FTIR spectroscopy confirmed enhanced β-phase formation with CB addition, with the fraction increasing from ~76% in pristine films to ~90% in 0.6 wt.% CB films. Under a dynamic load of 6 N at 1 Hz, the 0.6 wt.% CB composite delivered a peak open-circuit voltage of 3.65 V and a power density of 1.5 mW/cm 3 , comparable to poled P(VDF-TrFE) composites but achieved here without any electrical poling. These findings establish CB as a low-cost, scalable filler that induces self-poling and significantly improves energy conversion efficiency. The demonstrated method provides a pathway for lightweight, flexible nanogenerators suitable for next-generation wearable electronics and ultralow-power sensing devices.