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HIGHLIGHTS • The electrical transport of the metallized vein networks is mimicked from the material transport function of the leaf vein networks. • The vein-like transparent conducting electrodes show ultralow sheet resistance < 0.1 Ω □ −1 , broadband optical transparency > 80%, and high current density transport capability > 6000 A cm −2. • The metal consumption for the metallization of the leaf veins can be as low as 4 g m −2 .

It is demonstrated that spacer fabrics made of polyester can be coated with Al-doped ZnO (AZO) as thermoelectric (TE) material and conductive silver as contact material to enable smart textiles. An atomic layer deposition process was used for the AZO coating and the conductive silver paste was manually applied. A TE generator and cooling based on the Seebeck and Peltier effect can be observed if a temperature difference or direct current is applied, respectively. Both effects were proven to exist and evaluated. The Seebeck coefficient was determined of up to 50 µV · K−1 and a TE power of about 0.2 µW was generated. Without additional active heat dissipation or cooling, a temperature difference between both spacer fabric surfaces of up to 12 K was achieved. By changing the polarity of the electrical contacts it can significantly be shown that the cold-warm side is changed, as expected for a Peltier element. We observed experimentally the Peltier effect using a single element as well as electrically interconnected sample pairs, the latter could be important for the cooling application. Additionally, the heat transport through the spacer fabrics was tested and showed that there is no heat equalization between the surfaces via air and filaments at temperatures up to 50 °C. The Peltier effect as a fundamental TE effect, that enables site-specific and on-demand cooling applications, has not yet been comprehensively investigated using spacer fabrics and AZO as TE material. These investigations predict that AZO on spacer fabrics hold the special potential to enable flexible and textile solid-state cooling applications.

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