On the contact behavior of micro-/nano-structured interface used in vertical-contact-mode triboelectric nanogenerators

The triboelectric nanogenerator (TENG) has attracted enormous amount of attention in the research community in recent years because of its simple design, high energy conversion efficiency, broad application areas, a wide materials spectrum, and low-temperature easy fabrication. A key factor that dictates the performance of the TENGs is the surface charge density, which can be taken as a standard to characterize the matrix of performance of a material for a TENG. The triboelectric charge density can be improved by increasing the effective contact area, and in order to increase the contact area in a limited device size, micro-/nano-structures are often designed at the contact surfaces. Expert knowledge in contact mechanics, especially in adhesion and detachment mechanisms of the micro-/nano-structured interface, is thus becoming essential for a better understanding of the impact of interfacial design on the power generation of TENGs. Such an emerging field provides a platform for electrical engineers, chemical engineers, and mechanicians to share knowledge and build collaborations, which will enable the TENG researchers to pursue new design philosophies to achieve enhanced performance. In this paper, systematical numerical studies on the adhesive contact at the micro-/nano-structured interface are presented. We use a numerical simulation package in which the adhesive interactions are represented by an interaction potential and the surface deformations are coupled by using half-space Green's functions discretized on the surface. The results confirmed that the deformation of interfacial structures directly determines the pressure-voltage relationship of TENG, and it can be seen that our numerical results provided a better fit with the experimental data than the previous studies.