Extensive attention has been focused on thermoelectric performance optimization of SnTe because of its potential in waste heat recovery. Here, we fabricate high thermoelectric performance Se/Cd codoped SnTe octahedral particles by microwave-stimulated solvothermal method. The SnTe-based octahedral particles have sizes ranging from several micrometers to hundreds of nanometers, forming dense bulks after spark plasma sintering. Combined with the strong point defect scattering by Se and Cd dopants, a low thermal conductivity of 1.8 W m K at 773 K is obtained in the Se/Cd codoped SnCdTeSe sample. Se and Cd dopants can optimize the band structure of SnTe and boost the power factors, resulting in a promising peak ZT of ∼0.78 at 773 K in the Se/Cd codoped SnCdTeSe sample, which is significantly higher than those of undoped SnTe and Se-doped SnTe samples.

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Pristine GeTe shows promising thermoelectric performance but is limited by the high carrier concentration (n H) from Ge vacancies and thermal conductivity. Herein, Cu/Sb was chosen as codopants to suppress the high n H and to decrease thermal conductivity. In this condition, a promising zT of ∼1.62 under 773 K was acquired in the Ge0.85Te­(CuSb)0.075 system proposed in this paper/work. Results show that as the dopant concentration increases, the power factor rises due to the reduction of the n H to ∼1 × 1020 cm–3. Apart from this, the total thermal conductivity also declines from ∼7.4 W m–1 K–1 to ∼1.59 W m–1 K–1 originating from an ultralow lattice thermal conductivity, in which the multiscatter mechanism from grain boundaries and point defect disperses the frequency phonons differently. The findings in this paper combine thermal and electronic strategies and lay the foundation to develop Pb-free thermoelectric materials.

GeTe-based materials usually possess brilliant thermoelectric performance through band degeneracy and optimized carrier concentration. In this study, Ti doping is effective for the realization of band degeneracy. However, the high carrier concentration after Ti doping limited the enhanced thermoelectric performance. Accordingly, Sb was used to optimize hole carrier concentration. Combined with the decreased thermal conductivity, the enhanced power factors, due to band degeneracy and carrier concentration optimization, result in a high zT of 1.60 in Ge0.92Ti0.01Sb0.07Te. The achieved high zT demonstrates that the p-type Ti/Sb co-doped GeTe compounds are promising as mid-temperature thermoelectric materials.

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