Effect of Concentration of Electrolyte on Thermoelectric Properties of Electrodeposited Bi2Te3 Thin Films

Abstract The current thread of work focuses on tuning the properties of nano-structured Bi₂Te₃ films for thermoelectric applications, by optimizing electrodeposition conditions such as deposition potential, pH of electrolyte, temperature and concentration of the precursors in the solvent. In this paper, small coagulated masses of Bi₂Te₃ dendritic nanostructures were electrodeposited on a stainless-steel substrate under previously optimized deposition potential and pH conditions while changing the concentration of Bi³⁺ ions in the electrolyte (varied from 2.5 mM to 15 mM). Cyclic Voltammetry studies revealed that the material was deposited irreversibly at all concentrations. The effect of varying the concentration is indicated by a shift in the current peaks for oxidation and reduction peaks. A series of scanning electron micrographs revealed the evolution of beautiful small coagulated masses of dendritic structures as a function of the concentration of electrolyte. Thermoelectric properties such as the Seebeck coefficient up to -45.81 µV/K and power factor up to 311 µW/cmK² have been achieved for the deposited films. The results reveal significant variation in thermoelectric properties as a function of the concentration of Bi³⁺ in the electrolyte through changes in the surface morphology and stoichiometry of the films. The analysis also revealed ideal concentrations of precursor ions to obtain Bi₂Te₃ as the dominant phase.