Morphological Analysis and Properties Evaluation of Electrodeposited Thick BiSbTe Films with Cooperative Interactions among Multiple Additives

As a cost-effective method, electrodeposition has been widely applied to synthesize materials for the fabrication of micro thermoelectric devices. However, it is hard to obtain smooth, compact and high-performance p-type BiSbTe films when the thickness becomes higher. In this work, multiple additives consist of PVA and saccharin sodium are firstly introduced into the electrolyte bath with the assistance of KCl for electrodeposition. The influence of different additives on reduction kinetics, morphology, stoichiometry and crystalline structure has been thoroughly explored. Besides the electrolyte concentration and the deposition potential, the pulse duration for pulsed deposition also significantly affects the stoichiometry. The smooth, compact and well-adherent films with ideal composition were successfully deposited for the thickness range from 4 to 100 μm. Crystallite size was much refined, and lattice strain slightly increased with the cooperative reaction of multiple additives. The measured Seebeck coefficient reached around 262 25 μV K-1 for the deposited film with multiple additives, while that of the film with absence of additives was about 156 14 μV K-1. The electric resistivity increased from 66 μΩ•m to 150 μΩ•m when PVA and saccharin sodium were introduced, but decreased to 81 μΩ•m after increasing the electrolyte conductivity through adding KCl.