Size‐Dependent Piezoelectric Properties of Electrospun BaTiO₃ for Enhanced Energy Harvesting

Abstract In this study, electrospinning is used to fabricate a nanofibrous structured mixture of barium and titanium precursors dissolved in poly(vinylpyrrolidone). Two separate experimental designs are conducted to optimize the reduction of fiber diameter with minimum defects. The first focuses on the optimization of the solution properties and electrospinning parameters. The second is employed to optimize environmental conditions to further reduce the fiber diameter. Morphological analysis shows a minimum average fiber diameter of 77 ± 15 nm with minimal beading. The as‐spun nanofibers are subsequently calcinated to produce barium titanate nanofibers with an average diameter of 45 ± 9 nm. As expected, the average grain size increases as the heat treatment duration increases. Piezoresponse force microscopy reveals that the fiber diameter is inversely related to the d₃₃ piezoelectric coefficient. Individual crystallites of 25 nm in size along the axis of the 48 nm fiber exhibit d₃₃ coefficients as high as 76 pm V⁻¹. A flexible piezoelectric device composed of nanofibers with an average diameter of 45 nm embedded within polydimethylsiloxane produces a maximum voltage and power output of 7.94 V_p–p and 1.95 µW cm⁻², respectively, at a load resistance of 3.33 MΩ and a strain of 0.16%.