Triboelectric nanogenerators from fundamentals to applications

Triboelectric nanogenerators (TENGs) represent an innovative approach to energy harvesting, enabling the conversion of mechanical energy into electrical energy through contact electrification and electrostatic induction. This review comprehensively covers the fundamental principles of TENGs, starting from the fundamental mechanisms of contact electrification, including electron transfer, ion transfer, and material transfer models. The review discusses four primary operation modes-vertical contact separation, lateral sliding, single-electrode, and freestanding-each with distinct operational characteristics and potential applications. Theoretical models, including equivalent circuit and quasi-electrostatic models used to predict TENG output are examined. Strategies to enhance energy harvesting and transfer efficiencies are discussed. The article concludes by discussing the wide-ranging applications of TENGs, from wearable electronics and biomedical devices to large-scale systems for environmental energy harvesting. This review serves as a comprehensive resource for researchers, providing both fundamental knowledge and insight into the latest technological advances in TENGs to guide future developments in this rapidly evolving field.