Thermoelectric performance of smart textiles: Influence of graphene nanoplatelet concentration and textile substrate

This research investigates the thermoelectric (TE) characteristics of eight electrically conductive textiles (CTs) coated with a polyurethane (PU)-based coating paste using screen printing. The study analyses two primary variables: the textile structure, including woven and knitted fabrics, and the concentration of a graphene nanoplatelet (GNP)-based paste at 5 %, 7 %, 10 %, and 15 % (w/v). The physical and chemical properties of the materials are characterised using field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). A washing test protocol is used to evaluate washability and its impact on the TE characteristics of the CTs after 1, 5, 10, 15, and 20 wash cycles. The findings confirm the durability of the coating, as the CTs maintain consistent TE performance after 20 washes. The results indicate that the concentration of the active material exerts a greater influence on the analysed parameters than the textile structures, although the textile architecture significantly affects the quality of the coating. The highest Seebeck coefficient is achieved with the lowest GNP concentration (5 % w/v), yielding values of 18 ± 7 μVK −1 for the knitted fabric and 15 ± 2 μVK −1 for the woven fabric. On the other hand, the knitted fabric with the highest concentration of active material (15 % GNP w/v) exhibits the highest power factor (PF) of 0.9 nWm −1 K −2 . The main novelty of this study lies in the successful translation of the conductive and thermoelectric functionality of thin-film nanocomposites onto distinct flexible textile surfaces, offering a promising route for wearable energy harvesting and thermal sensing applications. Moreover, this is the first report of a coated knitted fabric operating as a thermoelectric material. • TE traits assessed on woven and knitted fabrics with varied GNP content. • Coated textiles retain TE properties after 20 domestic wash cycles. • 15 % GNP in knits yields highest power factor: 0.9 nWm −1 K −2 . • First report of a TE response in coated knitted textile. • Approach enables washable, flexible TE textiles for wearables.