Charge engineering in contact electrification and triboelectric nanogenerators: From fundamental mechanisms to performance enhancement

Contact electrification-derived triboelectric nanogenerators (TENGs) have emerged as a promising technology for energy harvesting. In either contact electrification or TENGs, charge engineering plays a crucial role in realizing their specific demands. Here, this review provides a comprehensive overview of the recent advances in contact electrification and TENGs, with a specific focus on the fundamental charge behavior during contact electrification and the strategies for improving surface charge density and TENG performance. Since the steady-state charge density is governed by both charge generation and dissipation, different charge transfer mechanisms and dissipation pathways are individually discussed, along with the effective approaches to enhance charge storage capability. Furthermore, this review outlines the strategies for boosting surface charge density and overall TENG performance from multiple perspectives, including material design, device architecture, circuit management, and working conditions. The versatile applications of high-performance TENGs are also highlighted in areas, such as power supplies, self-powered sensors, high-voltage sources, and blue energy harvesting. Finally, we present perspectives on the remaining challenges and future development of TENGs, aiming to inspire further research efforts in addressing these issues. Hopefully, this review will provide a better and more comprehensive understanding of contact electrification and TENG technology.