The lone pair in Ⅳ-Ⅵ compounds plays a significant role on tuning the phonon and electron transport for excellent thermoelectric performance. Here, we theoretically reveal a unique lone-pair distortion feature in Al-doped GeTe and further experimentally demonstrate the reduction of lattice thermal conductivity by Al doping. Due to the reduction of phonon velocity and enhanced anharmonicity, together with other phonon scattering mechanisms of point defects and stacking faults, an ultralow lattice thermal conductivity of ∼ 0.21Wm^-1 K^-1 at 773 K can be obtained in Al-doped GeTe. Besides, owing to the distorted distribution of Al-3s lone-pair electrons, the Al also show unusual p-type doping behavior in GeTe. By systemically combining the doping effects of Al, Sb and Pb, we can obtain a high figure of merit (ZT) of 2.21 at 773 K and a high average ZT of 1.51 within 300-773 K in the Ge_0.74Al_0.02Pb_0.1Sb_0.1Te. This study demonstrates the impact of lone-pair distortion on enhancing the ZT of GeTe, which also paves a new path way for developing other high-ZT thermoelectric materials.

Ⅳ-Ⅵ 化合物中的孤对电子在调节声子和电子传输以实现优异的热电性能方面起着重要作用。在这里，我们从理论上揭示了 Al 掺杂的 GeTe 中独特的孤对畸变特征，并进一步通过实验证明了 Al 掺杂降低了晶格热导率。由于声子速度的降低和非谐性的增强，以及点缺陷和堆垛层错的其他声子散射机制，超低晶格热导率约为 0.21Wm ^-1 K ^-1在 773 K 下可以在 Al 掺杂的 GeTe 中获得。此外，由于 Al-3s 孤对电子的扭曲分布，Al 在 GeTe 中也表现出不寻常的 p 型掺杂行为。通过系统地结合 Al、Sb 和 Pb 的掺杂效应，我们可以在 773 K 下获得 2.21的高品质因数 ( ZT )，在 Ge _0.74 Al _0.02 Pb _0.1 Sb 中在 300-773 K 范围内获得 1.51的高平均ZT _0.1 Te。该研究证明了孤对畸变对提高GeTe的ZT的影响，这也为开发其他高ZT热电材料铺平了新的途径。