Re-induced synergistic modulation of electrical and thermal transport in Cu/Br co-doped SnSe2 thermoelectric materials

Abstract

Transition-metal doping is considered as an effective strategy to improve the thermoelectric performance of SnSe₂-based semiconductors, since it can simultaneously optimize electronic transport and phonon scattering. Herein, Re was introduced into the Sn-rich Cu/Br co-doped SnSe₂ (SCSB) system. Microstructural characterizations reveal partial Re incorporation into the SnSe₂ lattice together with Re precipitates, while first-principles calculations using a hypothetical Re-for-Cu substitution configuration show a reduced band gap and enhanced DOS accumulation around the band edges, suggesting favorable electronic-structure modulation. Finally, the 0.75% Re-doped SCSB sample achieves a peak zT of ∼0.78 at 773 K, reaching a competitive level among reported n-type SnSe₂-based thermoelectric materials prepared by solid-state reaction and spark plasma sintering procedure. This work demonstrates that transition-metal doping is an effective and facile strategy for the synergistic optimization of electrical and thermal transport in SnSe₂-based systems.