Pseudo-binary layered compound ⅣVI-V₂VI₃ families show great promise for application in thermoelectrics. Herein, through introducing iodine in GeSb₂Te₄, several synergistic effects come into being and contribute to outstanding thermoelectric performance. The I^Te donor-like defects suppress the hole carrier concentration from 5.72 × 10²⁰ cm^–3 to 2.80 × 10²⁰ cm^–3. First-principles calculations reveal that iodine doping increases the band gap from 0.253 eV to 0.302 eV and contributes to valence band convergence. Seebeck coefficient value reaches up to 135.7 μV/K at 773 K, and the power factor values are entirely boosted in the whole temperature region, reaching a maximum value of 12.4 μW⸱cm^–1⸱K^–2 in GeSb₂Te_3.96I_0.04. Moreover, iodine doping simultaneously reduces the lattice and electronic thermal conductivity, leading to the greatly reduced total thermal conductivity from 2.89 W⸱m^–1⸱K^–1 in pristine sample to 0.89 W⸱m^–1⸱K^–1 in GeSb₂Te_3.84I_0.16 at 323 K. Finally, a maximum zT ∼ 1.12 at 773 K and an average zT ∼ 0.62 over 323–773 K are achieved in GeSb₂Te_3.88I_0.12. This work puts forward an effective strategy to synergistically optimize phonon and carrier transport properties of pseudo-binary compounds through halogen doping, which may be effective in other similar material systems.

中文翻译：

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协同效应导致碘掺杂伪二元层状 GeSb2Te4 的高热电性能


伪二元层状化合物 IV.VI-V₂VI₃ 族在热电技术中显示出巨大的应用前景。在此，通过在 GeSb₂Te₄ 中引入碘，产生了多种协同效应，并有助于实现出色的热电性能。I^Te 供体样缺陷抑制了空穴载流子浓度，从 5.72 × 10²⁰ cm^–3 到 2.80 × 10²⁰ cm^–3。第一性原理计算表明，碘掺杂将带隙从 0.253 eV 增加到 0.302 eV，并有助于价带收敛。在 773 K 时塞贝克系数值达到 135.7 μV/K，并且功率因数在整个温度区完全提高，在 GeSb₂Te_3.96I_0.04 中达到最大值 12.4 μW⸱cm^–1⸱K^–2。此外，碘掺杂同时降低了晶格和电子热导率，导致总热导率从 2.89 W⸱m^–1⸱K^–1 在 323 K 时从 GeSb₂Te_3.84I_0.16 中的 0.89 W⸱m^–1⸱K^–1 大幅降低。最后，在 GeSb₂Te_3.88I_0.12 中，在 773 K 时实现最大 zT ∼ 1.12，在 323-773 K 上实现平均 zT ∼ 0.62。这项工作提出了一种有效的策略，通过卤素掺杂协同优化伪二元化合物的声子和载流子传输特性，这可能在其他类似的材料系统中有效。