Structure and Dimension Effects on the Performance of Layered Triboelectric Nanogenerators in Contact-Separation Mode.

A triboelectric nanogenerator (TENG) is a potential solution for providing high output power by continuously harvesting ambient energy, which is expected to sustainably charge a battery for the new era-the era of the Internet of things and sensor networks. Generally, the existence of parasitic capacitance has been considered to be harmful in its output performance. Here, we systematically investigate the effects of structure and dimension of a TENG on its performance from the point view of parasitic capacitance by fabricating two types of layered TENGs with considering the dissimilarity of the two dielectric materials, symmetrical (ABBA) and alternate (ABAB) layered structure (SYM-TENG and ALT-TENG). Theoretical models of the two types of layered TENGs are proposed for illustrating their differences in parasitic capacitances and output characteristics. Larger parasitic capacitance enables the TENG to accommodate higher triboelectric charge density while reducing the internal impedance and maximum power density. Furthermore, the parasitic capacitance will be enhanced with the decreasing dimension of the devices. The effect of parasitic capacitance on output characteristics of the two kinds of structures are verified in vacuum. Our findings not only establish an optimization methodology for the output performance of TENGs but also provide an insight into the process of triboelectrification.