Antimony telluride (Sb2Te3) is a chalcogenide material used in thermoelectric applications. The deposition of thin films of Sb2Te3 requires a precisely controlled process to achieve a desirable high thermoelectric figure of-merit. The optimization of the thermal co-evaporation process for p-type Sb2Te3 thin-film onto plastic substrates (Kapton© polyimide) for thermoelectric applications is reported. The influence of deposition parameters and composition on thermoelectric properties was studied, seeking optimal thermoelectric performance. Energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy and Raman spectroscopy all confirmed the formation of Sb2Te3 thin films. Seebeck coefficient (up to 190 μVK−1), in-plane electrical resistivity (8–15 μΩm), carrier concentration (1×10^19–7×10^19 cm−3) and Hall mobility (120–180 cm2V−1s−1) were measured at room temperature for the best Sb2Te3 thin-films.