Laser-Tunable Noncontact Triboelectric Nanogenerators: A Novel Approach for Surface Charge Regulation and Enhanced Lifetime

The output performance of triboelectric nanogenerators (TENGs) largely depends on the density of electrons on the surface of the triboelectric materials, which is usually generated by the direct contact of two solid materials. Here, a novel method is proposed to regulate the surface charges of materials without physical contact. A laser-tunable noncontact triboelectric nanogenerator (LTNC-TENG) is fabricated, enabling the dynamic regulation of the surface states of materials through laser irradiation to optimize the performance of TENGs. In the experiment, TiO₂, SiO₂, and VO₂ LTNC-TENGs are designed and prepared. The results show that under low-energy laser irradiation, the open-circuit voltage (<i>V</i>_OC) and short-circuit transferred charge (<i>Q</i>_SC) increase, primarily due to the enhancement of the surface state energy levels induced by laser irradiation. As the laser energy increases beyond the laser-induced damage threshold (LIDT) of the films, induced damage occurs, generating abundant high-temperature plasma and resulting in decreased <i>V</i>_OC and <i>Q</i>_SC. Building upon these findings, a single-electrode mode LTNC-TENG is developed where voltage jumps occur when laser energy exceeds the film's LIDT. Furthermore, an electron cloud-potential well model is proposed, describing the approach of atoms from two different materials under laser irradiation without direct contact. This model elucidates the detailed mechanism of laser-induced charge transfer and reveals the "precursor" process of contact electrification. This study contributes to a deeper understanding of the underlying mechanisms of contact electrification and provides a theoretical foundation for the development of more advanced and noncontact TENGs, with largely enhanced lifetime.