A promising thermoelectrics In4SnSe4 with a wide bandgap and cubic structure composited by layered SnSe and In4Se3

The wide-bandgap cubic-structure semiconductor In 4 SnSe 4 can be regarded as a product of compositing two typical layered thermoelectric materials SnSe and In 4 Se 3 . Remarkably, In 4 SnSe 4 inherited low thermal conductivity from its parent materials. To advance the potential thermoelectric property of In 4 SnSe 4 , we systematically investigated its crystal structure and the origin of the intrinsic low thermal conductivity. In 4 SnSe 4 crystallized in a cubic phase (space group P a 3 ¯ ), with the lattice parameters of a = b = c = 12.66 Å. The anisotropy of In Se bonds in the lattice determined the complex structure of In 4 SnSe 4 with 72 atoms in the primitive cell. More importantly, sound velocity and elastic properties unclosed the strong anharmonicity in In 4 SnSe 4 , 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 In 4 SnSe 4 to improve the electrical transport properties. This work indicated that the complex wide-bandgap semiconductor In 4 SnSe 4 with cubic phase and intrinsic low thermal conductivity was a new promising thermoelectric material with appropriate doping. • The wide-bandgap cubic-structure In 4 SnSe 4 composited by layered SnSe and In 4 Se 3 is a promising thermoelectric material. • The lone-pair electrons from In + mainly cause the strong anharmonicity and suppress the heat transport in In 4 SnSe 4 . • Br is proved to be an effective dopant for n -type In 4 SnSe 4 .