Defect-mediated work function regulation in graphene film for high-performing triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) demonstrate an attractive pathway to directly convert broadband mechanical energy into electrical energy for a green and clean energy source. Triboelectric material design with tailored work function has played a critical role in enhancing the output performance of TENGs. However, regulating the work function of triboelectric materials still remains challenging due to the limited particle/group/ion doping rate. Here, we reported a simple defect-mediated strategy (DMS) to regulate the work function of graphene film (positive triboelectric material) by different contents of oxygen and carbon defects derived at annealing temperatures from 500 ºC to 3000 ºC. Our DMS features a continuous and wide-range tunable work function from 4.68 eV to 4.49 eV and the as-assembled TENGs produce output voltages and currents up to 190 V and 14 μA, respectively. The efficient work function regulation of this type establishes a set of fundamental considerations in triboelectric material design, especially the two-dimensional materials, to enhance the energy harvesting and sensing performances of TENGs.