In dopant enabled resonant level for thermoelectric enhancements in PbSnGeTe3

Resonant level engineering is an effective strategy to increase the Seebeck coefficient of thermoelectric semiconductors for high performance. Herein, we report a significant enhancement of the thermoelectric performance of PbSnGeTe3 over a wide temperature region through the In doping induced resonant level. Due to the simultaneously strengthened effective mass by inducing resonant levels nearby the Fermi level and decreased carrier concentration, a considerably improved Seebeck coefficient is obtained in In-doped PbSnGeTe3 and thereby the greatly increased power factor. The decreased carrier concentrations resulting from In substitution can also suppress the electronic thermal conductivity for a decreased thermal conductivity. The enhanced power factor and reduced thermal conductivity finally contribute to an extraordinarily high average ZT of 0.93 between 300 and 773 K in PbSnGeTe3. These observations demonstrate the viability of resonant levels in advancing thermoelectric materials with intrinsically high carrier concentrations.