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 \(\overline{3 }\) 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 (Bi0.96Sb0.04)2Se2.7Te0.3 crystal was reduced by a factor of ~ 8.0 compared to pristine BiSe3. Additionally, the power factor and figure of merit of the (Bi0.96Sb0.04)2Se2.7Te0.3 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.
