Tribological-behaviour-controlled direct-current triboelectric nanogenerator based on the tribovoltaic effect under high contact pressure

Dynamic metal-semiconductor Schottky contact interfaces suffer from wear even in low-friction direct-current triboelectric nanogenerators (DC-TENGs), which may affect their working stability and limit their practical applications. In this study, the mechanism and relationship between triboelectrification and tribological characteristics of the metal-semiconductor heterojunction interface with a ball-on-flat configuration under a high contact pressure were systematically studied to simultaneously obtain the high triboelectric output and low wear rate of the tribological-behaviour-controlled DC TENG (TCDC-TENG). The working mechanism of the TCDCTENG could be attributed to the tribovoltaic effect. An increased normal load and sliding frequency enhanced the triboelectric output while increasing the wear loss of the TCDC-TENG. Furthermore, both the triboelectric output and wear loss per unit time increased with the increase in the applied friction power, which was a product of the coefficient of friction (CoF), normal load (FN), and sliding speed (v). By adding polyalphaolefin SpectraSyn 4 as a lubricant, the CoF was lowered from 0.76 to 0.16, and the wear loss considerably decreased by 99.5% after 20,000 cycles of reciprocating sliding, while maintaining almost constant DC output voltage. This study not only presents the strong correlation between triboelectrification and tribology characteristics based on the tribovoltaic effect but also provides a new strategy for the semiconductor-based DC-TENGs for achieving a stable DC triboelectric output and wear resistance.