A descriptive model of thermoelectric transport in a resonant system of PbSe doped with Tl

Thermoelectric properties are governed by classic Boltzmann transport equations. This often sets limits for how much each material can be optimized for thermoelectric application. The resonant effect from dopants in certain systems presents one of a few successful strategies to work outside this classic limit. We studied the resonant effect from Tl in PbSe and developed a Boltzmann transport model to understand the changes in the Seebeck coefficient and mobility brought by resonant levels at different temperatures, which has not been discussed in the available literature. We found the most critical feature of resonant levels for thermoelectrics is their central energy position and its best location is near the band edge slightly into the conducting band. Our model also confirmed that it is possible to achieve moderate improvement of performance with resonant levels in systems similar to PbSe.