Boosting thermoelectric performance of SnTe by selective alloying and band tuning. (April 2022)

• Record Type: Journal Article
• Authors: Zhang, Yu; Li, Jun; Hu, Weiwei; Yang, Xinru; Tang, Xinfeng; Tan, Gangjian
• Is Part Of: Materials today energy. Volume 25(2022)
• Publication Date: 2022-04
• Subjects: SnTe thermoelectrics -- Selective alloying -- Band convergence -- Thermal conductivity; Energy development -- Periodicals; Energy industries -- Periodicals; Power resources -- Periodicals; Energy policy -- Periodicals; Energy development; Energy industries; Energy policy; Power resources; Electronic journals; Periodicals; 621.042
• DOI: 10.1016/j.mtener.2022.100958
• Languages: English
• ISSNs: 2468-6069

Abstract

Abstract: SnTe-based compounds have attracted increasing attention in recent years as lead-free thermoelectric materials. However, the thermoelectric performance of pristine SnTe is poor because of its overhigh lattice thermal conductivity and low Seebeck coefficient. In this study, we demonstrate that SnSe alloying considerably frustrates heat conduction in SnTe while preserving high charge carrier mobilities, by taking GeTe alloying as a comparative study. Based on these findings, we proceed to substitute Sn atoms by Cd in SnTe–SnSe alloys. This proves to be an efficient way of converging the two valence bands of SnTe, leading to remarkably improved Seebeck coefficients with the highest value approaching 200 μV/K at elevated temperatures. Consequently, the thermoelectric dimensionless figure of merit ZT reaches ∼0.9 at 873 K for the sample with nominal composition of Sn0.96 Cd0.04 Te0.88 Se0.12, which is over 60% improvement over pristine SnTe. Our work highlights the importance of selective alloying and band tuning in engineering bulk thermoelectric materials. Graphical abstract: This work reports that by combining selective alloying with band tuning, a maximum ZT of 0.9 at 873 K is attained in Sn0.96 Cd0.04 Te0.88 Se0.12 compound. Image 1 Highlights: Anionic site Se alloying considerably frustrates heat conduction in SnTe while preserving high charge carrier mobilities. Cd doping leads to pronounced valence band convergence that yields an ultrahigh Seebeck coefficient ~200 μV/K. By selective alloying and band tuning, a maximum ZT of 0.9 at 873K is achieved in Sn0.96 Cd0.04 Te0.88 Se0.12 .