High-performance piezoelectric nanogenerators featuring embedded organic nanodroplets for self-powered sensors

Piezoelectric nanogenerators with excellent electromechanical coupling effects are in great demand for self-powered Internet-of-Things (IoT) devices. In this work, a novel solid-liquid nanocomposite-based piezoelectric nanogenerator (SL-PENG) with unprecedented properties was developed by employing 1H,1H,2H,2H-perfluorodecyltriethoxysilane (FDTS) droplets as liquid fillers. Through the combination of solvent selection and solvent evaporation protocols, highly deformable FDTS nanodroplets with a controllable droplet size were uniformly distributed in a polyvinylidene fluoride (PVDF) matrix, thereby improving the toughness of the polymer matrix. FDTS nanodroplets form strong intermolecular hydrogen bonds with PVDF chains to promote the transformation of α-phase to polar β-phase, while stabilizing the liquid phase that prevents FDTS nanodroplets from fracture and exudation to a polymer network. The synergistic contribution of the β-phase content and stress transfer ability significantly improves the output performance of SL-PENG, which is proved by the experimental results and COMSOL simulation. Remarkably, this SL-PENG generates a maximum peak-to-peak voltage and current as high as 62 V and 3.2 μA, respectively, corresponding to a power density of 35 μW cm⁻², which demonstrates remarkable superiority to other PENGs. Moreover, this SL-PENG is demonstrated as part of a monitoring device for the wireless sensor network, realizing the detection and response of physiological signals, and showing broad potential application prospects in the field of IoT.