Triboelectric energy harvesting device, so called triboelectric generator (TEG), generates electricity by repeated friction of two surfaces with different triboelectric properties. Thanks to its relatively high output power and simple device fabrication process, this energy harvesting scheme has been actively investigated as a power source for small electronic devices or wireless sensors. Until now, persistent efforts have been focused on how to increase the output power of the TENGs. In particular, modulation of dielectric permittivity of the friction surface have been demonstrated as one of the facile methods to effectively boost the output power of TENGs.
In this work, we report the performance of TENG realized by electrospun nanofibers on the friction surface. Different polymers were electrospun on the electrode substrate, such that one surface is coated with triboelectrically positive nanofibers and the other is coated with triboelectrically negative ones. In particular, by forming core-shell nanofiber on the one of the contact surface, where the core contains a polymer with high dielectric permittivity and the shell is coated with triboelectrically opposite one compared with the opposing friction surface, the performance of TENG was greatly enhanced. Furthermore, the nanofiber formation on the friction surface also increases the surface area of the friction surface, effective increasing surface charge density, resulting in high current density and voltage. The method introduced here can be potentially adopted for developing textile based energy harvesting utilizing triboelectric effect.