Polymer-based triboelectric nanogenerators: Materials, characterization, and applications

Triboelectric nanogenerators (TENGs), a nascent field in energy conversion technologies, provide a novel approach to producing electrical energy from mechanical motion in the surrounding environment.Polymers play a key role in the functioning of TENGs through their exceptional triboelectric properties, with most triboelectric active materials being polymeric with negative affinity potential. Since there are many scientific issues that are not well understood yet regarding the working mechanism and fundamental issues regarding the role of polymers in TENGs, this review covers TENG fundamentals and effects of environmental parameters and provides a deep analytical analysis of important literature studies of TENGs. Although TENGs generate high voltage, their current generation is usually in the microamp range. Modifying polymer dielectric materials has been much investigated to enhance the output performance of TENGs. This article provides a comprehensive review of various polymer modification categories and associated performance enhancement with an analysis and comparison of research results to help grasp the big picture on the role of polymer modification on TENG performance. Specifically, the source of triboelectrification and updated knowledge about their working principle, and the quantified comparison of triboelectric material are discussed. Then physical nano and microstructure and the effect of TENG material shape on the output are brought into the discussion. Equally, the important role of chemical modification of triboelectric active polymer by way of categorization of methods and their effect on electricity generation is put under focus. In order to enhance the triboelectric negativity of polymer properties, it is useful to introduce chemical groups with high negativity, such as halogens. This can be achieved through several methods, including using a sulfur backbone or casting fluorinated self-assembly monolayers (SAMs), and the impact on TENGs' performance is explored. Furthermore, the addition of fillers to polymers is a proven technique for increasing their dielectric constant, which is emphasized as particularly significant.