GeTe systems are excellent p-type thermoelectric materials at medium temperatures (500–800 K). Recently, their electronic properties were enhanced by band convergence of L and Σ valence bands, which increased the power factor at 500–800 K. However, there are only a few thermoelectric materials suitable for lower-temperature waste-heat recovery applications, and their demand is rapidly increasing. Herein, we demonstrated that the well-known L and Σ bands of GeTe and the additional Δ band converge at a desirable energy level to a very narrow energy range as a result of fine-tuning the crystal symmetry and composition by forming a GeTe-Sb₂Te₃ alloy. Alloying additionally facilitates a decrease in the bandgap, thereby increasing the near-room-temperature power factor. The GeTe-Sb₂Te₃ alloy achieved very high room-temperature and maximum power factors of 2.6 mW m⁻¹ K⁻² at 300 K and 3.3 mW m⁻¹ K⁻² at 423 K, respectively, despite GeTe being a medium-temperature thermoelectric material. Thus, we confirmed the applicability of GeTe as a thermoelectric material at room temperature. This study facilitates the development of high-performance near-room-temperature thermoelectric materials based on existing medium-temperature systems.

GeTe 系统是中温 (500–800 K) 下优异的 p 型热电材料。最近，由于 L 和 Σ 价带的能带收敛增强了它们的电子特性，从而提高了 500-800 K 的功率因数。然而，适用于低温废热回收应用的热电材料很少，它们的需求正在迅速增加。在这里，我们证明了 GeTe 众所周知的 L 和 Σ 能带以及附加的 Δ 能带在理想的能级收敛到非常窄的能量范围，这是通过形成 GeTe-Sb 微调晶体对称性和组成的结果₂ Te ₃合金。合金化还有助于减小带隙，从而提高接近室温的功率因数。GeTe-Sb 尽管 GeTe 是一种中温热电材料，但₂ Te ₃合金 在 300 K 和423 K 时分别达到了 2.6 mW m ^-1 K ^-2和 3.3 mW m ^-1 K ^{-2 的}非常高的室温和最大功率因数. 因此，我们证实了 GeTe 在室温下作为热电材料的适用性。这项研究促进了基于现有中温系统的高性能近室温热电材料的开发。