Increasing Surface Charge Density By Intrinsic Charge Layer Inclusion for High Performance Efficient Triboelectric Nanogenerators

Abstract

In recent years, mechanical transducers for energy harvesting, particularly triboelectric nanogenerators (TENGs) have been conceived as a practical power source due to its simple, compact and high efficiency for energy harvesters. Charge injection and retention in thin film dielectric layers remain critical issues in realizing TENGs as a sustainable power source. In this work, we have presented a novel technique to boost the output electrical performance of triboelectric nanogenerators by the inclusion of charge accumulation layer. This thin film layer allows to store and accumulate the charges generated by triboelectrification and refill the charges on every triboelectrification process of the vertical contact separation TENG mechanism. This increase in the stored charges has an effect of inducing many free charges on the electrodes of the device in a much larger quantity and gives rise to a much higher electrical output power. A proof of concept TENG structure is devised to validate the electrical output performance. Experimental results show that, the devised structure reaches an open circuit voltage of 600 V demonstrating 25 times enhancement than the conventional triboelectric devices in ambient conditions. The in–situ surface characterization implemented using atomic force microscopy (AFM) reveals the charge retention characteristic due to the presence of the charge accumulation layer. This technical outcome will significantly facilitate the future research in increasing the charge density to efficiently provide higher output power attractive to charging applications for portable electronics/ wearables and large-scale harvesting without massive volume. By this technique, numerous friction-based operation challenges including lack of uniform contact, material loss through wear, high sensitivity to humidity, and output power storage have been resolved.