An insight into experimental and theoretical thermoelectric property of antimony and tellurium-doped Bi₂Se₃ single crystals

The thermoelectric properties of Bi₂Se₃ single crystals were investigated with Sb and Te co-doping using a modified vertical Bridgman method, complemented by theoretical studies. X-ray diffraction confirmed the rhombohedral crystal structure with an R 3¯ m space group. High-resolution X-ray diffraction (HR-XRD) analysis revealed a high degree of periodicity, threefold symmetry, and c-axis growth through θ − 2θ scans. Hall effect and Seebeck coefficient measurements indicated n-type conductivity across all samples, with a carrier concentration of approximately 10²⁵ m⁻³. At 300 K, the electrical resistivity of the (Bi_0.96Sb_0.04)₂Se_2.7Te_0.3 crystal was reduced by a factor of ~ 8.0 compared to pristine BiSe₃. Additionally, the power factor and figure of merit of the (Bi_0.96Sb_0.04)₂Se_2.7Te_0.3 compound improved by 3 times and 1.2 times, respectively. Theoretical studies using density functional theory (DFT) supported these experimental findings, showing that substituting Sb in Bi₂Se₃ enhances its electrical properties.