Triboelectric charging sequence induced by surface functionalization as a method to fabricate high performance triboelectric generators.

Two different materials, apart from each other in a triboelectric series, are required to fabricate high performance triboelectric generators (TEGs). Thus, it often limits the choices of materials and causes related processing issues for TEGs. To address this issue, we report a simple surface functionalization method that can effectively change the triboelectric charging sequence of the materials, broadening material choices and enhancing the performance of TEGs. Specifically, we functionalized the surfaces of the polyethylene terephthalate (PET) films either with poly-l-lysine solution or trichloro(1H,1H,2H,2H-perfluorooctyl) silane (FOTS). Consequently, the PET surfaces were modified to have different triboelectric polarities in a triboelectric series. The TEGs, fabricated using this approach, demonstrated the maximum Vopen-circuit (Voc) of ∼330 V and Jshort-circuit (Jsc) of ∼270 mA/m(2), respectively, at an applied force of 0.5 MPa. Furthermore, the functionalized surfaces of TEGs demonstrated superior stability during cyclic measurement over 7200 cycles, maintaining the performance even after a month. The approach introduced here is a simple, effective, and cost-competitive way to fabricate TEGs, which can also be easily adopted for various surface patterns and device structures.