Ultrarobust, hierarchically anisotropic structured piezoelectric nanogenerators for self-powered sensing

Despite significant efforts to develop piezoelectric nanogenerators (PENGs), scalable manufacture of polymeric PENGs with highly sensitive and stable piezoelectric output remains a great challenge. Here, we propose a noncovalent assembly-mediated solid-state drawing strategy for the electrical treatment-free fabrication of high-performance PENGs with hierarchically anisotropic structure. Along with the stress-induced anisotropic alignment of glycine modified-molybdenum disulfide nanosheets, the strong intermolecular interactions and confinement between 2D nanosheets and polyvinylidene fluoride (PVDF) dipoles can aggressively induce the self-polarized β-phase transition of PVDF in a favorable direction. The resulted nanocomposite without extra electrical treatment exhibits remarkable piezoelectric performance (d33 =24.9 pC N-1) and extraordinary mechanical performance (tensile strength of 213.3 MPa, toughness of 85.8 MJ m-3), far surpassing most reported polymeric piezoelectric materials. Taking these advantages, the PENGs-based self-powered physiological sensors show highly sensitive and stable output signals, satisfying the requirements of tiny and large human motions monitoring. This work opens an avenue toward large-area compliant and low-energy manufacturing of diverse energy harvesting devices and self-powered sensory systems.