Electrophoretic assembly and electronic transport properties of rapidly synthesized Sb2Te3 nanoparticles

With the recent advances in thermoelectric (TE) technology, there is an increasing demand to develop thick films that would enable large-scale TE devices. Assembly of TE-films from size and morphology-controlled nanoparticles has been a challenging issue that can be addressed by the use of electrophoretic deposition (EPD) technique. In this work, morphology-controlled Sb2Te3 nanoparticles were synthesized through microwave-assisted thermolysis, which were subsequently used for EPD of TE films on specially developed glass-substrates. The electronic transport properties were measured in the temp-range of 22-45 °C. The as-made EPD films showed a high initial resistance, ascribed to high porosity and the presence of surface oxide/passivating layers. The impact of two types of small organic molecules -as hexanedithiol and dodecanethiol, on the electronic transport was investigated, resulting in a significant improvement in the conductivity of the films. The XPS analysis suggests that the thiols bind to the surface of nanoparticles through formation of sulfides. Seebeck coefficient in the range of +160 to +190 µV/K was measured, revealing the p-type transport through the deposited films. Finally, a power factor of about 2.5 µW/K2.m was estimated the first time for p-type EPD films, revealing the potential of the developed nanoparticles and substrate, the small molecule additives and the EPD process presented in this work.