LAUSR

Abstract Single crystal tin selenide (SnSe) has attracted much attention for its excellent thermoelectric performance. However, polycrystalline SnSe exhibits unsatisfactory figure‐of‐merit due to the inferior electrical properties, especially for n‐type SnSe. In this work, a high concentration of Br doping (6–12 atm%) on the Se site effectively increases the Hall carrier concentration from 1.6 × 1017 cm−3 (p‐type) in undoped SnSe to 1.3 × 1019 cm−3 (n‐type) in Br‐doped SnSe0.88Br0.12, leading to an increased electrical conductivity close to that of a single crystal. Combined with the decreased lattice thermal conductivity due to the enhanced phonon scattering by composition fluctuation and dislocations, a peak ZT of ≈1.3 at 773 K, together with the enhanced average ZT is obtained in SnSe0.9Br0.1 along the hot pressing direction.