Thermoelectric properties of PEDOT/PSS films prepared by a Gel-film formation process

•Developing a technique for fabricating PEDOT/PSS films (gel-film formation process).•The film thickness can be controlled in the range of 1 to 30 μm.•The gel-film formation enhanced thermoelectric properties without commonly used pre- and post-treatment steps.•The values of σ=1070S/cm and S=16.0μV/K were achieved for d=1.1μm, using ethanol as the gelling solvent.•Ethanol plays the important roles of removing excess PSS and inducing subsequent gelling. We have developed a technique for fabricating films of the thermoelectric material, PEDOT/PSS, with enhanced thermoelectric properties via a gel-film formation process. The salient features of the process are 1) the absence of any commonly used pre- and post-treatment steps and 2) wide film thickness control. The new process is different from direct film-formation processes such as the spin-coating and drop-casting methods. The film thickness can be controlled in the range of 1 to 30 μm. In this study, we investigated the dependence of the electrical conductivity (σ) and Seebeck coefficient (S) on the film thickness (d). While the value of σ increased with decreasing d, S decreased slightly with decreasing d. By this process, values of σ=1070S/cm and S=16.0μV/K were achieved for d=1.1μm, using ethanol as the gelling solvent. Ethanol plays the important roles of removing excess PSS and inducing subsequent gelling.