Electrochemical Synthesis of an Organic Thermoelectric Power Generator

Energy harvesting through residual heat is considered one of the most promising ways to power wearable devices. In this work, thermoelectric textiles were prepared by coating the fabrics, first with multiple-wall carbon nanotubes (MWCNTs) by using the layer-by-layer technique and second with poly(3,4-ethylenedioxythiophene) (PEDOT) deposited by electrochemical polymerization. Sodium deoxycholate and poly(diallyldimethylammonium chloride) were used as stabilizers to prepare the aqueous dispersions of MWCNTs. The electrochemical deposition of PEDOT on the MWCNT-coated fabric was carried out in a three-electrode electrochemical cell. The polymerization of PEDOT on the fabric increased the electrical conductivity by ten orders of magnitude (through the plane), establishing an excellent path for electric transport across the fabrics. In addition, the fibers showed a Seebeck coefficient of 14.3 μV K^-1, which is characteristic of highly doped PEDOT. As a proof of concept, several thermoelectric modules were made with different elements based on the coated acrylic and cotton fabrics. The best generator made of 30 thermoelectric elements using acrylic fabrics exhibited an output power of 0.9 μW with a temperature difference of 31 K.