High thermolectric properties of disordered Ge0.8-ySn0.2MnyTe semiconductor

Abstract

For layered GeTe-based materials, the typical strategy to reduce the thermal conductivity of the crystal lattice is to introduce atomic disorder, increase the lattice non-harmonicity, and maximize the fluctuations of the quality/stress field in the sample. Since Sn/Mn can easily form solid solutions in the GeTe matrix, the degree of disorder in the sample is much higher than the level reported in IV-VI alloys in the past, which leads to a strong phonon scattering and a sharp decrease in the lattice thermal conductivity over the entire temperature range. In addition, Mn plays a significant role in changing the valence band structure of GeTe, i.e., Mn doping enhances the convergence of the light valence band and the heavy valence band and the change of the bandgap, significantly increasing the Seebeck coefficient of the GeTe matrix, resulting in a significant improvement in the thermoelectric performance of the Sn/Mn co-doped synthesized GeTe-based materials. Finally, we found that treating the sample with layered disorder is an effective method to improve the thermoelectric performance, and this study has certain reference value for the development of novel toxic-free, high-performance thermoelectric materials.