Authors: Caballero-Calero, O; Borca-Tasciuc, DA; Martinez-Moro, R; Gorog, A; Mohner, M; Borca-Tasciuc, T; Martin-Gonzalez, M

Electrochim. Acta. vol: 269. page: 0013-4686.
Date: APR 10. 2018.
Doi: 10.1016/j.electacta.2018.03.025.

Bi2.0Te2.7Se0.3 is the most widely used thermoelectric n-type leg for large-scale cooling applications. However, as-grown electrodeposited Bi2Te3-ySey films typically have a Seebeck coefficient around a third of the bulk value, which sometimes can be improved with thermal annealings. In this work, we report as-grown Bi2Te3-ySey films having a Seebeck coefficient of approximately half the value of bulk without additional thermal treatments. All samples reported were deposited in baths containing no additives, sodium lignosulfonate (SLS), or both SLS plus ethylenediaminetetraacetic acid (EDTA) with a concentration of 1 M HNO3 (pH of 0 +/- 0.1) and 0.6 M HNO3 (pH of 0.3 +/- 0.1). For each scenario, the deposition was carried out at two different temperatures (0 degrees C and 5 degrees C). Seebeck values of -120 mu V K-1 have been measured for as-grown films with an optimum morphology and stoichiometry (Bi2Te2.7Se0.3), which is similar to 50% of the value obtained for this composition in bulk and the highest among as-grown electro-chemically deposited films reported to date. These results are an incentive to revisit and further explore the chemistry behind the electrodeposition of bismuth telluride selenide films to improve the performance of electrodeposited thermoelectric films. (C) 2018 Elsevier Ltd. All rights reserved..