Tribological Properties and Electrification Performance of Patterned Surface for Sliding-Mode Triboelectric Nanogenerator

The triboelectric nanogenerator (TENG) can be used to transform kinetic energy into electricity based on the triboelectric effect and electrostatic induction. In most cases, the micro-/nanostructures are introduced on the polymer surface of sliding-mode TENG, but their effectiveness on electrical output as well as durability of the device are really ambiguous. Little research has been devoted to investigating the relationship between the tribological properties and electrical performance of TENG with a patterned surface so far. In this paper, the pillar arrays are fabricated through lithography, deep reactive ion etching, and replication techniques and a test platform for both tribological and electrical performance for sliding-mode TENG is constructed as well. Then, the effects of the pillar pitch on the coefficient of friction, mass loss, and open-circuit voltage are investigated experimentally. The reported results suggest that the open-circuit voltage has a clear dependence on the sliding distance of sliding-mode TENG with a certain patterned surface. Initially, the open-circuit voltage increases with the increasing sliding distance due to the increment of the contact area. Then, the open-circuit voltage diminishes with the increasing sliding distance because of the transfer of the material with negative charges from polyimide film to Cu surface. Finally, the open-circuit voltage remains almost steady with the increasing sliding distance, because the number of negatively charged wear debris of polyimide on the Cu surface is almost constant during this time. On the other hand, with the increment of the pillar pitch, the average coefficient of friction is found to be decreased, whereas the mass loss of the polymer film increases. The maximum values of the open-circuit voltage and the steady-state open-circuit voltage decrease with the increasing pillar pitch.