This study presents a method to enhance the thermoelectric performance of bulk thermoelectric materials by embedding dense dislocation arrays in grain boundaries. The research focuses on $ Bi_{0.5}Sb_{1.5}Te_{3} $ (BST) materials, which are commonly used in thermoelectric applications due to their high thermoelectric efficiency. The study involves the preparation of BST ingots, melt spinning, and spark plasma sintering to create samples with excess Te. The samples are then characterized using various techniques, including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, to analyze their microstructure and thermoelectric properties. The thermoelectric properties of the samples are measured in both directions parallel and perpendicular to the pressing direction. The results show that the Te-excess BST samples exhibit significantly higher thermoelectric performance, with a maximum figure of merit (zT) of 1.86 at 320 K, which is about 11% higher than that of the stoichiometric BST samples. The enhanced performance is attributed to the dense dislocation arrays embedded in the grain boundaries, which act as scattering centers for phonons, thereby reducing the lattice thermal conductivity and increasing the Seebeck coefficient. The study also includes detailed calculations of the lattice thermal conductivity using the Debye-Callaway model, which considers various scattering mechanisms such as Umklapp phonon-phonon scattering, point-defect scattering, and boundary scattering. The results show that the dislocation arrays significantly reduce the lattice thermal conductivity, contributing to the improved thermoelectric performance. The research demonstrates that the dense dislocation arrays embedded in grain boundaries can significantly enhance the thermoelectric performance of BST materials, making them promising candidates for high-performance thermoelectric applications. The findings provide a new approach to improving the efficiency of thermoelectric materials through microstructural engineering.This study presents a method to enhance the thermoelectric performance of bulk thermoelectric materials by embedding dense dislocation arrays in grain boundaries. The research focuses on $ Bi_{0.5}Sb_{1.5}Te_{3} $ (BST) materials, which are commonly used in thermoelectric applications due to their high thermoelectric efficiency. The study involves the preparation of BST ingots, melt spinning, and spark plasma sintering to create samples with excess Te. The samples are then characterized using various techniques, including X-ray diffraction, scanning electron microscopy, and transmission electron microscopy, to analyze their microstructure and thermoelectric properties. The thermoelectric properties of the samples are measured in both directions parallel and perpendicular to the pressing direction. The results show that the Te-excess BST samples exhibit significantly higher thermoelectric performance, with a maximum figure of merit (zT) of 1.86 at 320 K, which is about 11% higher than that of the stoichiometric BST samples. The enhanced performance is attributed to the dense dislocation arrays embedded in the grain boundaries, which act as scattering centers for phonons, thereby reducing the lattice thermal conductivity and increasing the Seebeck coefficient. The study also includes detailed calculations of the lattice thermal conductivity using the Debye-Callaway model, which considers various scattering mechanisms such as Umklapp phonon-phonon scattering, point-defect scattering, and boundary scattering. The results show that the dislocation arrays significantly reduce the lattice thermal conductivity, contributing to the improved thermoelectric performance. The research demonstrates that the dense dislocation arrays embedded in grain boundaries can significantly enhance the thermoelectric performance of BST materials, making them promising candidates for high-performance thermoelectric applications. The findings provide a new approach to improving the efficiency of thermoelectric materials through microstructural engineering.