Multifunctional TE-Fabric based on interlayer synergy: A flexible thermoelectric fabric for thermal management and self-powered sensing

Flexible thermoelectric materials hold great promise for wearable electronics and self-powering. However, p-type thermoelectric materials that combine multifunctionality, high performance and long-term stability are scarce. Here, we developed a flexible p-type TE-Fabric with excellent stress/thermoelectric sensing and electrical heating properties through molecular engineering strategies. It is worth noting that during the preparation of TE-Fabric, we found that dopamine modification could enable the ordered orientation of PEDOT:PSS. The dopamine-modified PEDOT: PSS treated with multi-layer superposition HCl can greatly improve the electrical conductivity of thermoelectric materials (2040.8 S·cm −1 ), while retaining the partial orientation of PEDOT. The TE-Fabric obtained through layer-by-layer self-assembly achieves a double breakthrough in Seebeck coefficient (27.3 μV·K −1 ) and electrical conductivity (2431.2 S·cm −1 ), while exhibiting excellent mechanical flexibility (elongation at break of 71.1 %, breaking strength of 14.8 MPa) and high-performance stability. Taking advantage of TE-Fabric's high conductivity characteristics, we found that TE-Fabric was able to produce a high efficiency thermal response (93.1 % electro-thermal conversion efficiency, 177.1 °C) at low voltage (5 V). At the same time, the flexibility and high-performance stability supported the advantage of TE-Fabric in stress sensing, with a fast response (0.213 to 0.218 s). The thermoelectric device constructed by alternating six sets of flexible p-type TE-Fabric and flexible n-type nickel sheets produces an output voltage of 9 mV at a temperature difference capable of 60 K. Based on this feature, we combine the thermoelectric generator with a mask to make a breath detection sensor device. By outputting different voltage signals, we can monitor the health status of human body in real time during deep breathing, static breathing, rapid wheezing and coughing. This pioneering work opens up new avenues for the development of flexible P-type TE materials with high stability and versatility.