Theory and applications of high-voltage triboelectric nanogenerators

As an emerging energy-harvesting technology, triboelectric nanogenerators (TENGs) have made rapid progress in the past decade. Alongside the well-known self-powering behavior, TENGs also have another unique feature: high-voltage and low-current output. It is relatively easy for TENGs to achieve voltage outputs of hundreds and even thousands of volts, while the current output remains on the order of several micro-amperes. This brings opportunities to develop safe high-voltage applications. This review introduces the fundamental theories of voltage generation by TENGs and summarizes the strategies to boost TENG voltage up to tens of kilovolts. The applications of these high-voltage TENGs (HV-TENGs) in physical, chemical, and biological fields are also reviewed in detail. Finally, the opportunities and challenges for HV-TENGs are discussed.