Development of graphene/MWCNT/Ag2Se hybrid thermoelectric materials with different concentrations of PEDOT:PSS for low-temperature applications

Studies in low-temperature applications in the fields of medicine and wearable technologies are limited to thermoelectric works with commercial poly(3,4-ethylenedioxy-thiophene):polystyrenesulfonate (PEDOT:PSS) aqueous solutions. Unlike other studies, in this study, the effects of adding graphene, multi-walled carbon nanotube (MWCNT) and silver selenide into PEDOT:PSS at different concentrations in the production of semiconductor polymer inks on the thermoelectric properties were examined using Taguchi analysis. In the examination without adding additives, as the ratio of PEDOT:PSS increased from 1 % to 3 % and 5 %, 2.50 and 4.92 times increase in electrical conductivity and 1.19 and 1.49 times increase in the Seebeck coefficient were observed, respectively. P- and n-type inks were produced in three different concentrations using four different materials. According to the results of the study, to obtain p-type material with good performance, the concentration of PEDOT:PSS in the mixture must be high and the Ag₂Se concentration must be low, and also to get a high-performance n-type material, the concentration of Ag₂Se must be as high as the homogeneous mixture allows, and PEDOT:PSS concentration must be low. When the highest Power Factor and Figure of Merit results were evaluated, PPp9 was found for p-type material and PPn2 was found for n-type material, and it is considered that these inks are suitable for printing with 3D printing technology.