Full Thermoelectric Characterization of Stoichiometric Electrodeposited Thin Film Tin Selenide (SnSe).

Matthew R Burton,James Mcgettrick,Iris Nandhakumar,Matthew J Carnie,Tianjun Liu,Connor A Boyle,Oliver Fenwick

doi:10.1021/acsami.0c06026

Abstract

Tin selenide (SnSe) has attracted much attention in the thermoelectric community since the discovery of the record figure of merit (ZT) of 2.6 in single crystal tin selenide in 2014. There have been many reports since of the thermoelectric characterization of SnSe synthesized or manufactured by several methods, but so far none of these have concerned the electrodeposition of SnSe. In this work, stoichiometric SnSe was successfully electrodeposited at -0.50 V vs SCE as shown by EDX, XPS, UPS, and XRD. The full ZT of the electrodeposits were then measured. This was done by both a delamination technique to measure the Seebeck coefficient and electrical conductivity which showed a peak power factor of 4.2 and 5.8 μW m-1 K-2 for the as deposited and heat-treated films, respectively. A novel modified transient 3ω method was used to measure the thermal conductivity of the deposited films on the deposition substrate. This revealed the thermal conductivity to be similar to the ultralow thermal conductivity of single crystal SnSe, with a value of 0.34 W m-1 K-1 being observed at 313 K.

Highlights

The effects of climate change require greener forms of energy to be developed, while around a sixth of industrial energy is lost as heat.[1]
In this study we report the successful electrodeposition of thin films of SnSe
∼8 μm thick films of SnSe were fabricated onto a Au substrate via a simple electrodeposition process

Summary

■ INTRODUCTION

The effects of climate change require greener forms of energy to be developed, while around a sixth of industrial energy is lost as heat.[1]. For electrical and Seebeck measurements, the electrodeposited films were delaminated onto 2 mm glass using 2 part epoxy as previously reported in the literature.[33−38] For thermal conductivity measurements, samples were deposited onto Linseis Thin Film Analyzer “ZT chips” with a contact layer of 15 nm layer Cr evaporated onto the sample area followed by 75 nm of Au. Full details of the measurement process are in the Supporting Information and elsewhere.[39,40] The Linseis Thin Film Analyzer measures total thermal conductance of all materials deposited onto the measurement chip plus the contribution of the chip itself, so the thermal conductivity of. Electrical conductivity and Seebeck coefficients were measured on a commercial ULVAC ZEM3 in a helium atmosphere; silver conductive paint (Electrolube) was added to the top and bottom to make electrical contacts. In-plane thermal conductivity was measured under vacuum on a test chip by a modified in-plane 3ω method with a Linseis Thin Film Analyzer (see the Supporting Information for full details)

■ RESULTS AND DISCUSSION

■ CONCLUSION

■ ACKNOWLEDGMENTS

■ REFERENCES