Investigation of diamond-like carbon films as a promising dielectric material for triboelectric nanogenerator

Highlights: • The superior triboelectric properties of DLC film is successfully demonstrated. • Ultrathin DLC films could be achieved with excellent tribological, mechanical and dielectric properties. • Incorporating DLC as dielectric material significantly enhances the durability of the sliding-TENG. • DLC favors design simplification of TENG by virtue of its dual role as triboelectric and an anti-friction surface. -- Abstract: Modern electronic systems are smarter and compact, yet highly efficient at greater speeds. These systems require just a minimal amount of power which have indeed encouraged new technologies to scavenge energy from the surrounding environment. Triboelectric nanogenerator (TENG) is one such device which has demonstrated a cost-effective, reliable and efficient technology for harvesting natural mechanical energy. However, the durability and stability of TENG is a critical attribute for the high output efficiency at a consistent rate and strongly depends on the frictional characteristics of triboelectric materials. In the first of its kind, a detailed investigation is done on the ability of diamond-like carbon (DLC) film to be a potential triboelectric material for TENG applications. DLC film was deposited on the substrate (electrode) of a contact-separation based TENG (CS-TENG) using plasma-based ion implantation and deposition (PBII&D) technique. The performance evaluation of TENG consisting of DLC film - polymer as the triboelectric pairs revealed some very interesting results. Hydrogenated DLC (H-DLC) and PTFE (Polytetrafluoroethylene) based TENG produced the highest output with a peak current of 3.5 μA and a power density of up to 57 mW/m² over other conventional dielectric pairs like Al-PTFE, Polyimide (Kapton^®)-PTFE, and Kapton-Al. Furthermore, fluorine doped DLC (F-DLC) film produced a moderate output with Kapton, and PTFE, indicating its benefits for TENG applications. In the durability assessment, the DLC deposited rotary sliding-TENG exhibited excellent durability by producing a stable output current for 3 h at a reduced friction coefficient. This study serves as a noteworthy beginning towards the understanding of the triboelectric behavior of DLC films from TENGs perspective and could significantly contribute to designing of a highly durable, cost-effective, low friction and efficient sliding-TENG.