Correlation of Microstructural Properties with Thermoelectric Performance of Bi0.5Sb1.5Te3 Films Fabricated by Electroplating

This study shows for the first time, the correlation between the microstructural properties (chemical composition and its homogeneity) and the thermoelectric properties for p-type Bi0.5Sb1.5Te3 electroplated films (10-15 mu m thickness). High microstructural quality of Bi0.5Sb1.5Te3 electroplated films (a close to stoichiometry chemical composition with its high homogeneity elements distribution) was achieved by using an additive in the plating solution (sodium ligninsulfonate) as a surfactant agent. A fine-grained microstructure of 280 nm to 1 mu m has been observed for these materials, which half that of the plated films without a surfactant. The thermoelectric properties of electrodeposited Bi0.5Sb1.5Te3 films obtained without microstructural optimisation, show modest Seebeck coefficient values of 20-120 mu V/K, electrodeposited film with an optimised microstructure exhibits very high values of Seebeck coefficient of 220-300 mu V/K.