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

Abstract The current thread of study focuses on tuning the properties of nanostructured Bi2Te3 films for thermoelectric applications, by optimizing electrodeposition conditions such as the deposition potential, pH of the 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 at 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. 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 a 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 the 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.