Nanoarchitectonics of High-Performance and Flexible n-Type Organic–Inorganic Composite Thermoelectric Fibers for Wearable Electronics

Since most conductive polymers are <i>p</i>-type, developing high-performance <i>n</i>-type organic-inorganic composite thermoelectric (TE) fibers is a great challenge. Herein, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)-coated Ag₂Te nanowires (PC-Ag₂Te NWs) were prepared by a liquid-phase reaction using PEDOT:PSS-coated Te nanowires (PC-Te NWs) as templates, and the PEDOT:PSS/PC-Ag₂Te NWs composite fibers were then prepared by wet spinning. As the content of PC-Ag₂Te NWs increases, the composite fiber changes from <i>p</i>-type to <i>n</i>-type. The PEDOT: PSS coating greatly improves the dispersibility of Ag₂Te NWs in the PEDOT: PSS matrix, resulting in an ultrahigh content of 87.5 wt % of PC-Ag₂Te NWs in the composite fibers, which exhibited a Seebeck coefficient of -61.3 μV K^-1 and a power factor of 65.3 μW m^-1 K^-2. The power factor value is higher than those of previously reported <i>n</i>-type composite TE fibers. Contrary to the estimated thermal conductivity in other reports, in this work, the thermal conductivity of the composite fibers was measured via a transient photoelectrothermal (TPET) technique. In addition, the composite fiber has good tensile properties and mechanical strength, elongating at a break of 47.37% and a tensile stress of 6.59 MPa. For an application demonstration, a self-powered temperature sensor was assembled, which can utilize the vertical temperature difference between the human body and the environment and respond quickly to a small temperature difference.