Highlights

« previous result | next result »

Electrodeposition of thermoelectric materials

PhD-research report

Hai P. Nguyen


 

Organizations:

• KU Leuven, Department of Metallurgy and Materials Engineering (MTM), Heverlee, Belgium

• imec / Holst centre, Eindhoven, The Netherlands

 

Abstract

Thermoelectric devices can directly convert thermal energy to electricity or pump heat up a temperature gradient. They are increasingly used as low-power power generators or coolers. Bismuth telluride (Bi2Te3) and antimony telluride (Sb2Te3) are the best thermoelectric materials working near room temperature. The electrodeposition of bismuth telluride and antimony telluride films has been investigated, mostly from acidic aqueous solutions. However, the poor solubility of tellurium(IV) and antimony(III) in aqueous media limits the deposition rate and causes difficulties in controlling the composition.

 

Bi2Te3

Bi2Te3 film (thickness 50 µm) deposited at a current density of -5.0 A/ dm2 from a solution containing 0.4 M Bi(NO3)3, 0.2 M TeCl4 and 0.5 M LiNO3 , at 50 °C, on Au/Si substrates.

 

The current limitation plaguing the electrodeposition of thermo-electric materials from aqueous solutions were solved by using new non-aqueous solutions using organic solvents (dimethyl sulfoxide (DMSO), ethylene glycol, molten acetamide). These solutions are able to maintain metal concentrations of up to 1 M, which is 200 times higher than in the conventional acidic solutions. From these electrolytes, bismuth telluride films with the correct stoichiometry could be grown at the highest rate up to date (100 µm/ h). By using cyclic voltammetry (CV), electrochemical quartz micro-balance (EQCM), and rotating (ring) disk electrodes (RDE, RRDE) we determined the mechanisms and the kinetics of the electrochemical reactions during electrodeposition. In addition, by solving the problem of short-circuit created by the conductive seed layer, we developed a method to, for the first time, determine the Seebeck coefficient of electrodeposited films in their as-prepared condition.

 

Ref. : Hai P. Nguyen, Electrodeposition of thermoelectric materials, PhD thesis- KU Leuven, ISBN 978-94-6018-629-5 (March 2013).

 

For further information, please contact:

Prof. Jan Fransaer, Dept. MTM, KU Leuven (Belgium)

e-mail Jan.Fransaer@mtm.kuleuven.be

Bi2Te3 film (thickness 50 µm) deposited at a current density of -5.0 A/ dm2 from a solution containing 0.4 M Bi(NO3)3, 0.2 M TeCl4 and 0.5 M LiNO3 , at 50 °C, on Au/Si substrates.
Bi2Te3 film (thickness 50 µm) deposited at a current density of -5.0 A/ dm2 from a solution containing 0.4 M Bi(NO3)3, 0.2 M TeCl4 and 0.5 M LiNO3 , at 50 °C, on Au/Si substrates.

Downloads