Electronic structure ofCsBi4Te6: A high-performance thermoelectric at low temperatures

Recently, a novel narrow-gap semiconductor ${\mathrm{CsBi}}_4{\mathrm{Te}}_6$ has been discovered with greater potential for low-temperature applications than the best existing high-performance thermoelectrics, ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ and its alloys. Electronic structure calculations in this bulk system display reduced dimensionality of hole transport whose origin can be traced to the presence of Bi-Bi bonds (instead of Bi-Te and Te-Te bonds), unique for bismuth chalcogenide systems. This reduced dimensionality of charge transport along with the low thermal conductivity of this compound can explain the observed large thermoelectric figure of merit ZT in hole doped ${\mathrm{CsBi}}_4{\mathrm{Te}}_6.$