The wide-bandgap cubic-structure semiconductor In₄SnSe₄ can be regarded as a product of compositing two typical layered thermoelectric materials SnSe and In₄Se₃. Remarkably, In₄SnSe₄ inherited low thermal conductivity from its parent materials. To advance the potential thermoelectric property of In₄SnSe₄, we systematically investigated its crystal structure and the origin of the intrinsic low thermal conductivity. In₄SnSe₄ crystallized in a cubic phase (space group $Pa\overline{3}$), with the lattice parameters of a = b = c = 12.66 Å. The anisotropy of InSe bonds in the lattice determined the complex structure of In₄SnSe₄ with 72 atoms in the primitive cell. More importantly, sound velocity and elastic properties unclosed the strong anharmonicity in In₄SnSe₄, which contributed greatly to the low thermal conductivity. With first-principles calculations, it was found that the lone-pair electrons from In⁺ mainly caused the anharmonicity in the lattice. Additionally, Br was proved to be an effective dopant for In₄SnSe₄ to improve the electrical transport properties. This work indicated that the complex wide-bandgap semiconductor In₄SnSe₄ with cubic phase and intrinsic low thermal conductivity was a new promising thermoelectric material with appropriate doping.

宽带隙立方结构半导体In ₄ SnSe ₄可以看作是两种典型的层状热电材料SnSe和In ₄ Se ₃复合而成的产物。值得注意的是，In ₄ SnSe ₄继承了其母材的低导热性。为了提高In ₄ SnSe ₄的潜在热电性能，我们系统地研究了它的晶体结构和本征低热导率的起源。In ₄ SnSe ₄以立方相（空间群$磷\mathrm{一个}\overline{3}$)，晶格参数为a  =  b  =  c  = 12.66 Å。晶格中In Se键的各向异性决定了In ₄ SnSe ₄在原始晶胞中具有72个原子的复杂结构。更重要的是，声速和弹性特性揭示了In ₄ SnSe ₄中的强非谐性，这对低热导率有很大贡献。通过第一性原理计算发现，In ⁺的孤对电子主要引起晶格的非谐性。此外，Br 被证明是 In ₄ SnSe _{4的有效掺杂剂}以改善电传输性能。这项工作表明，具有立方相和本征低热导率的复杂宽禁带半导体In ₄ SnSe _{4是一种具有适当掺杂的新型有前途的热电材料。}