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, Sb2Si2Te6 and Bi2Si2Te6. 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 Bi2Si2Te6 to experience significant charge carrier scattering, whereas Sb2Si2Te6 is relatively unaffected by the phenomenon. Furthermore, extensive point defect scattering in Sb2Si2Te6 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.
Keywords: heterointerfaces; phase boundary scattering; point defects; thermal conductivity; thermoelectrics.