Multilayer assembly of electrospun/electrosprayed PVDF-based nanofibers and beads with enhanced piezoelectricity and high sensitivity

Abstract

Flexible high-performance piezoelectric nanogenerators (PNG) that can convert mechanical energy into electricity are crucial for the development of self-powered wearable electronic devices. In this work, a 3D multilayer assembly of flexible organic polypyrrole (PPy) electrodes, electrospun poly(vinylidene fluoride) (PVDF) nanofibers and electrosprayed CsPbBr3@PVDF beads was proposed for a high-performance PNG, wherein two layers of CsPbBr3@PVDF beads were inserted between the top/bottom PPy electrodes and PVDF nanofibers layer, respectively. The PPy electrodes were fabricated via vapour phase polymerization of pyrrole monomers on the surface of the electrospun PVDF nanofibers with FeCl3 acted as an oxidant. As for the active piezoelectric layers, both the PVDF nanofibers and CsPbBr3@PVDF beads possessed high fractions of β crystalline phase, i.e., 83.5% and 94%, respectively, which helps to provide favorable polarization response. Besides, the introduction of the globular CsPbBr3@PVDF particles also facilitated the stress excitation to the piezoelectric layers, thus leading to enhanced output performance and high sensitivity. Piezoelectric results showed that the 3D multilayer NFMs based PNG exhibited a high open-circuit voltage of 10.3 V and a short-circuit current density of 1.29 μA/cm2, and could detect a weak pressure as low as 7.4 Pa. Furthermore, the PNG based fabrics also demonstrated excellent ability to harvest energy from the temperature fluctuations through pyroelectric effect. The structuration method of embedding globular particles into electrospun PVDF NFMs may open up the feasibility of fabricating high-output PNG.