An electrostatically self-assembled fluorinated molecule as a surface modification layer for a high-performance and stable triboelectric nanogenerator

Abstract

Triboelectric nanogenerators (TENGs) that convert mechanical energy into electricity have been considered as an economical strategy for energy harvesting. Modification of the surface properties of triboelectric materials is a straightforward method to improve the performance of TENGs. In this study, for the first time, we demonstrate a promising strategy to improve the performance and stability of TENGs by using electrostatically self-assembled 1H,1H-perfluorooctylamine (F₁₅-NH₂) as the surface modification layer for the polydimethylsiloxane (PDMS) dielectric layer. Our results indicate that the protonated amine groups present on F₁₅-NH₂ can anchor onto the PDMS surface via electrostatic interactions, whereas adoption of a slow-drying procedure during film formation enables highly electronegative perfluoroalkyl chains to accumulate at the air interface, facilitating the formation of an ordered molecular arrangement that can induce a favourable surface dipole for efficient electron transfer between the electrode and the dielectric layer. Importantly, this strategy can be applicable to a large-area plastic-based TENG, and a remarkable power density up to 57.1 W m⁻² is achieved. To the best of our knowledge, the power density reported herein represents the highest value ever reported for solution-based chemically modified TENGs. The impressive output characteristics of the TENG enable 338 light-emitting diodes to be lit up instantaneously. More encouragingly, excellent durability of the TENG is attained when using a perylene diimide derivative-modified Ag layer as the electrode, exhibiting an almost unchanged V_oc over 240 000 operation cycles. Our findings highlight the importance of surface engineering via electrostatically self-assembled materials for realizing high-performance and stable TENGs with high reproducibility. The strategies demonstrated herein enable the mass production of surface modification layers through processes that are compatible with scalable roll-to-roll manufacturing techniques, which can accelerate the commercialization of low-cost printed TENG technology.