A high-performance flexible piezoelectric energy harvester based on lead-free (Na0.5Bi0.5)TiO3–BaTiO3 piezoelectric nanofibers

Abstract

Recently wearable energy harvesters have attracted great attention due to their vital importance in portable energy-harvesting and personal electronics. Here we report a high-performance flexible piezoelectric energy harvester based on superior environmentally friendly 0.93(Na_0.5Bi_0.5)TiO₃–0.07BaTiO₃ (NBT–0.07BT) nanofibers. High-quality lead-free NBT–0.07BT fibers were synthesized by a sol–gel based electrospinning method. X-ray diffraction (XRD), scanning electron microscopy (SEM), piezoresponse force microscopy (PFM), and high-resolution transmission electron microscopy (HRTEM) were utilized to characterize the morphologies, phase structures, domain structures, and local piezoelectric response. The NBT–0.07BT nanofibers, which were located at the morphotropic phase boundary (MPB), exhibited a pure perovskite structure and superior local piezoelectric response (the effective normalized strain constant d_33,eff reached up to ∼109 pm V⁻¹ for single NBT–0.07BT nanofibers). The flexible piezoelectric energy harvester based on the NBT–0.07BT nanofibers exhibited a high peak voltage output of ∼30 V under 1 MΩ load resistance when applying a dynamic load using a finger and the short-circuit peak current reached ∼80 nA. Upon periodic mechanical impact, electrical energy was repeatedly generated from the device to power a commercial light-emitting diode. The advantages of small size, ease of processing, high flexibility, and environmental friendliness make this lead-free piezoelectric device quite promising for application in portable electronics.