Tailoring the Thermoelectric Performance of the Layered Topological Insulator SnSb2Te4 through Bi Positional Doping at the Sn and Sb Cation Sites

초록

Ongoingresearch and development focus on emerging thermoelectricmaterials with enhanced performance, continually making the possibilityof waste heat recovery a reality. In this work, we engineer the thermoelectricproperties of the layered SnSb2Te4 topologicalinsulators. To date, there is little research reporting on these materialsas potential state-of-the-art thermoelectric materials. Thus, thereis a need to formulate effective strategies to realize this potential.Since these materials are known to have intrinsically low latticethermal conductivity, we shift our attention to improving the electricaltransport properties. For the first time, positional Bi doping atboth the Sn and Sb cation sites is adopted. The aliovalent and isovalentnature of Bi at these sites, respectively, is shown to cause significantimprovements in the performance of these layered materials. The electronicband structure of the pure and doped samples, where we consideredvarious occupancies, is studied whereby we reveal the occurrence ofband convergence and resonant levels resulting in a high power factorof & SIM;10.8 & mu;W cm(-1) K-2 at 623 K. Overall, a high ZT of & SIM;0.46 ata relatively lower temperature of 673 K is recorded. The potentialof these materials for thermoelectric applications is shown, especiallyin the case of Bi doping at the Sn cation site. Continued effortsto enhance the thermoelectric performance of these topological insulatorsare needed for them to gain a substantial competitive edge in comparisonto other state-of-the-art thermoelectric materials.

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