Electrochemical deposition of bismuth telluride thick layers onto nickel

C Lei,K.S Ryder,E Koukharenko,M Burton,Iris S Nandhakumar

doi:10.1016/j.elecom.2016.02.005

Abstract

Bismuth telluride (Bi2Te3) is the currently best performing thermoelectric (TE) material in commercial TE devices for refrigeration and waste heat recovery up to 200°C. Up to 800μm thick, compact, uniform and stoichiometric Bi2Te3 films were synthesized by pulsed electrodeposition from 2M nitric acid baths containing bismuth and tellurium dioxide on 1cm2 nickel (Ni) substrates at average film growth rates of ~50μm/h. Pre-treatment of the Ni substrate was found to significantly enhance the adhesion of Bi2Te3 material onto Ni while pulsed electrodeposition was used to increase the compactness of the material. To maintain a homogeneous composition across the thickness of the films, a sacrificial Bi2Te3 anode was employed. All deposits produced were n-type with a Seebeck coefficient of up to −80μV/K and an electrical conductivity of ~330S/cm at room temperature.

Highlights

Thermoelectric (TE) generators are devices that can directly convert heat into useful electrical energy using the Seebeck effect
These include low cost, high controllability over size, thickness, crystallinity [4], scalability, roomtemperature fabrication, and fast deposition rate which are suitable for producing thick films that can be incorporated into practical TE devices
Electrodeposition is carried from electrolyte solutions containing a ratio of [Bi3+]/[Te4+]= 1 by pulsed electrodeposition employing zero current resting pulses for 2-5s and deposition pulses for 10-100 ms at -0.01 V to -0.06 V vs. saturated calomel electrodes (SCEs) which were identified as the optimum electrodeposition conditions to grow thick layers of stoichiometric Bi2Te3 films at average film growth rates up to 50 μm/hour

Summary

Introduction

Thermoelectric (TE) generators are devices that can directly convert heat into useful electrical energy using the Seebeck effect. Electrochemical deposition provides an attractive route to the fabrication of high-quality TE materials such as bismuth telluride, offering several advantages over other methods. These include low cost, high controllability over size, thickness, crystallinity [4], scalability, roomtemperature fabrication, and fast deposition rate which are suitable for producing thick films that can be incorporated into practical TE devices. We describe the optimised electrochemical deposition conditions that were employed to produce uniform and compact and well adherent Bi2Te3 layers on Ni with thicknesses > 500 μm of stoichiometric composition that displayed excellent thermoelectric performance

Experimental

Results and discussion

CONCLUSIONS