Structural and Phase Analysis of Poly(vinylidene fluoride)/Poly(vinylidene fluoride-trifluoroethylene)-Based Ultra-responsive Piezoelectric Nanogenerators

Abstract

Studies on poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) blends primarily emphasize the β-phase of PVDF without considering the effects of chain length and lattice expansion caused by TrFE addition. Typically, peak intensity adjustments for Bragg’s equation are used to estimate β-phase content, neglecting pair distribution function analysis. Hence, this work addresses this gap through a comprehensive structural investigation using pair distribution function techniques, supported by Fourier-transform infrared spectroscopy and X-ray powder diffraction. Field emission scanning electron microscopy and atomic force microscopy analysis revealed disrupted spherulite growth, enhancing structural coherence and electrical properties. Characterization confirmed consistently increased β-phase crystallinity and reduced amorphous content compared to the reported literature. Diffraction and total scattering analysis validated the consistent β-phase content. Additionally, a thorough performance evaluation of the polymer blend was carried out, further establishing its potential for innovative applications. This study presents a detailed structural investigation of PVDF/PVDF-TrFE blends using complementary techniques, contributing additional insights into phase evolution and piezoelectric performance optimization. The optimized PVDF/PVDF-TrFE (1:2) blend achieved an open-circuit voltage of 14.7 V, a short-circuit current of 1.50 μA, and a power density of 16.15 μW/cm2. This output is sufficient to power up microsensor nodes for commercially available motion sensors and ultralow-power radar modules, demonstrating the potential of the device for the Internet of Things and related low-energy electronics. A voltage of 4.0 V was generated under a weak applied force of 0.2 N, denoting sufficient sensitivity for applications in touch sensors, soft robotics, and implantable medical devices.