Enhancing Near-Room-Temperature GeTe Thermoelectrics through In/Pb Co-doping

The traditional thermoelectric material GeTe has drawn much attention recently because of the reported high thermoelectric performance of the rhombohedral phase in lowtemperature ranges, where the split L and S band can be reconverged to have a small energy offset and thus high density of state effective mass according to the rhombohedral angle. In addition, In doping in GeTe is also reported to enhance the density of effective mass and therefore increase the Seebeck coefficient because of the induced resonant levels. In this work, In and Pb are doped in GeTe, and In doping leads to an increase in the rhombohedral angle and thus enhanced density of state effective mass in addition to the resonant effect. However, the improved Seebeck coefficient result from In doping is compensated for by a sharp reduction of Hall mobility, leading to no significant enhancement of electronic performance in the rhombohedral phase. By further Pb/Ge doping in the matrix Ge0.95In0.05Te for the optimization of carrier concentration and reduction of lattice thermal conductivity (as low as 0.7 W/mK), a zT as high as similar to 1.2 at 550 K and average zT of similar to 0.75 between 300 and 550 K are realized in this work, demonstrating GeTe as a promising candidate for near-room-temperature application.

Automated summary

GeTe has received much attention recently for its high thermoelectric performance, with In and Pb doping enhancing the density of effective mass and optimizing carrier concentration. The addition of Pb/Ge further reduces lattice thermal conductivity, leading to high zT values and demonstrating GeTe as a promising candidate for near-room-temperature applications.