Harnessing piezoelectric and flexoelectric synergies in one-dimensional heterostructure nanofibers for nano-energy harvesting and self-powered sensors

Piezoelectric materials are based on the conversion between mechanical and electrical energy, which is enormous potential for application in developing flexible self-powered electronics. The output performances of piezoelectric energy harvesters are determined by the energy transduction coefficient (d33 × g33). However, the piezoelectric materials simultaneously with large piezoelectric voltage constant (g33) and high piezoelectric coefficient (d33) are still a considerable challenge. Herein, we propose an innovative solution by constructing heterostructure BaTiO3-SrTiO3 nanofibers (BT-ST NFs) to improve d33 × g33 via a couple of piezoelectricity and flexoelectricity for enhancement in output performances. The combination of simulation and multi-angle characterization theoretically manifests that the heterostructure BT-ST NFs could significantly improve synergistic effect with the original BT-ST NFs piezoelectricity and strain gradient-induced flexoelectricity. Among all the components, the flexible piezoelectric energy harvesters (FPEH) with 15.0 wt% BT-ST@PDA/PVDF exhibits the best output voltage and current (∼149.2 V and ∼ 17.3 μA). Based on its excellent performance, the FPEH shows great potential in acquiring mechanical energy for self-power. It can be used to obtain energy from the wheel to power the capacitor and immediately power the sensor. This study provides a new route to design high-performance lead-free one-dimensional piezoelectric fillers for more diverse energy harvesting methods.