Atomic structures and electronic properties of different contact surfaces for CxFy–SiO2 triboelectric nanogenerator based on first-principles investigations

Modification of the dielectric friction layer materials is an ideal way to enhance the output performance of a triboelectric nanogenerator (TENG), but current research mostly focuses on the metal–polymer or metal–SiO₂ materials. In this work, we constructed different TENG models based on polymer C_xF_y–SiO₂ electret materials, and the electronic properties of the different contact surfaces were investigated using first principles. We found that the charge transfer in C_xF_y–SiO₂ materials occurred only at the contact interface, and it was partially affected by the terminal atoms near the SiO₂ interface. The charge transfer of the polymer C_xF_y that was in contact with the O-terminated SiO₂ achieved a more satisfactory effect. Among them, the II-C₃F₆–O model exhibited the highest amount of charge transfer because of the better hybridization of II-C₃F₆ with the O atoms of SiO₂ layer. Our study showed that instead of adding different types of dielectric friction layers, varying the configurations of the same types of dielectric friction layers is an alternative way to regulate charge transfer. Furthermore, this strategy could provide new ideas for enhancing the performance of TENGs.