Facile production of thermoelectric bismuth telluride thick films in the presence of polyvinyl alcohol

Abstract

Bismuth telluride is currently the best performing thermoelectric material for room temperature operations in commercial thermoelectric devices. We report the reproducible and facile production of 600 micron thick bismuth telluride (Bi₂Te₃) layers by low cost and room temperature pulsed and potentiostatic electrodeposition from a solution containing bismuth and tellurium dioxide in 2 M nitric acid onto nickel in the presence of polyvinyl alcohol (PVA). This was added to the electrolyte to promote thick layer formation and its effect on the structure, morphology and composition of the electrodeposits was investigated by SEM and EDX. Well adherent, uniform, compact and stoichiometric n-type Bi₂Te₃ films with a high Seebeck coefficient of up to −200 μV K⁻¹ and a high electrical conductivity of up to 400 S cm⁻¹ resulting in a power factor of 1.6 × 10⁻³ W m⁻¹ K⁻² at film growth rates of 100 μm h⁻¹ for potentiostatic electrodeposition were obtained. The films also exhibited a well defined hexagonal structure as determined by XRD.