Electronic structure and thermoelectric properties:PbBi2Te4and related intergrowth compounds

The layered $\text{PbTe}:{\text{Bi}}_{2}{\text{Te}}_{3}$ intergrowth compound, ${\text{PbBi}}_{2}{\text{Te}}_{4}$, and related materials are investigated using first-principles calculations and Boltzmann transport theory. The electronic structures of these compounds are closely related to those of the end points, especially ${\text{Bi}}_{2}{\text{Te}}_{3}$ but the band gaps are larger than those of ${\text{Bi}}_{2}{\text{Te}}_{3}$. The calculated thermopowers are comparable to those of ${\text{Bi}}_{2}{\text{Te}}_{3}$ at similar doping levels but extend to higher temperatures due to the larger band gaps with the implication that the thermoelectric performance of these compounds will be best at temperatures above the range of ${\text{Bi}}_{2}{\text{Te}}_{3}$.