Comparative Study of Thermoelectric Properties of Sb 2 Si 2 Te 6 and Bi 2 Si 2 Te 6 .

Charge carrier transport and corresponding thermoelectric properties are often affected by several parameters, necessitating a thorough comparative study for a profound understanding of the detailed conduction mechanism. Here, as a model system, we compare the electronic transport properties of two layered semiconductors, Sb 2 Si 2 Te 6 and Bi 2 Si 2 Te 6 . Both materials have similar grain sizes and morphologies, yet their conduction characteristics are significantly different. We found that phase boundary scattering can be one of the main factors for Bi 2 Si 2 Te 6 to experience significant charge carrier scattering, whereas Sb 2 Si 2 Te 6 is relatively unaffected by the phenomenon. Furthermore, extensive point defect scattering in Sb 2 Si 2 Te 6 significantly reduces its lattice thermal conductivity and results in high zT values across a broad temperature range. These findings provide novel insights into electron transport within these materials and should lead to strategies for further improving their thermoelectric performance.