Output Voltage Enhancement Strategies and Multi-Field Applications of Tribovoltaic Nanogenerators

Tribovoltaic nanogenerators (TVNGs) utilize the tribovoltaic effect of the heterojunction interface to directly convert mechanical energy into electrical energy. They have advantages such as direct current electricity output, low impedance, and high energy conversion efficiency. However, due to the low voltage output (the output voltage of unenhanced TVNGs is usually ∼10 mV to ∼1 V), it is difficult to directly power commercial electronic devices that require high operating voltage (usually more than 1.5 V). Therefore, enhancing their output voltage is the key to expanding their application range. In this Review, the working mechanisms of TVNGs at four types of interfaces, namely, metal-semiconductor interfaces, semiconductor-semiconductor interfaces, insulation layer intercalation composite interfaces, and liquid-solid interfaces, are analyzed from the perspectives of carrier transport mechanism and energy band theory. Then, the mechanisms and specific methods of enhancing their output voltage through material modification strategy and multi-physics field coupling strategy are mainly discussed. Furthermore, we summarize their applications in the fields of human motion and environmental mechanical energy harvesting as well as in the field of self-powered sensing, such as human posture monitoring and industrial equipment status monitoring. Finally, some challenges facing TVNGs are briefly pointed out, including the imperfect micro friction mechanism, the impact of dynamic impedance matching characteristics on output voltage, and the reliability and stability of operation in extreme environments. Some outlooks for future research are given. This Review provides guidance for the research and applications of high-performance TVNGs.