Electrodeposition of bismuth telluride thermoelectric films from a nonaqueous electrolyte using ethylene glycol

Abstract

Ethylene glycol was studied as an electrolyte for the electrodeposition of thermoelectric bismuth telluride films by cyclic voltammetry, rotating ring disk electrode and electrochemical quartz crystal microbalance (EQCM). The reduction of both Bi3+ and Te4+ ions proceeds in one step without the formation of intermediates at potentials more negative than +0.2V and +0.55V vs. SHE, respectively. The diffusion coefficients and the rate constants for reduction were found to be similar for Bi and Te. Stoichiometric Bi2Te3 films with a uniform composition profile were obtained from solutions containing up to 1M of Bi(NO3)3 and TeCl4, at current densities up to 5Adm−2 (∼102μmh−1). Both p- and n-type bismuth telluride films could be obtained, as confirmed by Seebeck coefficient measurements.