Y-ZnO Microflowers Embedded Polymeric Composite Films to Enhance the Electrical Performance of Piezo/Tribo Hybrid Nanogenerators for Biomechanical Energy Harvesting and Sensing Applications

Nowadays, hybrid nanogenerators (HNGs) have attracted much interest in mechanical energy-harvesting technology because of their assertable advantages in self-powered portable electronic devices. However, the HNG output performance is highly dependent on the active material, the structure of the device, the applied mechanical pressure, and so forth. In this regard, to develop a high-performance HNG, yttrium (Y)-doped zinc oxide (ZnO) microflowers (Y-ZnO MFs) were synthesized and embedded into polydimethylsiloxane (PDMS) for developing rationally designed composite films. Unlike the previously reported ZnO HNGs, the synthesized Y-ZnO MFs/PDMS-based HNG exhibits an improved electrical output because of the enhanced ferroelectricity of Y-ZnO MFs and the resultant increase of the charge density in the composite films. In addition, the effects of Y concentration on ZnO MFs and Y-ZnO MFs loaded into PDMS on the output performance of Y-ZnO MFs/PDMS HNG were studied systematically, and the optimized Y dopant concentration in ZnO MFs was found. Thus, the 0.5 mol % of Y-ZnO MFs and the 2.5 wt % of Y-ZnO MFs embedded in PDMS achieved a stable and enhanced performance. The obtained voltage (VOC), current (ISC), and instantaneous power density of the composite film-based HNG (Y-ZnO MFs/PDMS) were 247 V, 7 μA, and ∼6 W/m2, respectively. Furthermore, the practical and commercial applications of the proposed HNG were demonstrated by sensing and harvesting biomechanical motions available in everyday human activities and powering various portable electronics.