Understanding the role of additional Cu intercalation in electronic and thermal properties of p-type Cu_2.9Te₂-incorporated Bi_0.5Sb_1.5Te₃ thermoelectric alloys

While extensive research has explored Cu doping in n-type Bi₂(Te,Se)₃ for its beneficial effects on reproducibility and mobility, its impact on p-type (Bi,Sb)₂Te₃ remains incompletely understood. Recently, Saglik et al. demonstrated Cu_2.9Te₂ incorporation into Bi_0.5Sb_1.5Te₃ as a novel approach for simultaneous Cu doping and intercalation, surpassing prior studies focused solely on Cu doping at Bi/Sb sites. The influence of additional Cu intercalation on both electronic band parameters (density-of-states effective mass, deformation potential, and weighted mobility) and phonon scattering by point defects has yet to be investigated. Here, we employ the Effective Mass model to comparatively assess the impact of Cu intercalation on these band parameters relative to single Cu doping. Furthermore, the Callaway-von Baeyer and Debye-Callaway models are employed to evaluate the effect of Cu intercalation in scattering phonons. Our findings reveal that additional Cu intercalation effectively suppresses the lattice thermal conductivity of Bi_0.5Sb_1.5Te₃ to the amorphous limit, offering the potential to improve the figure-of-merit (zT) to ∼2.0 near 420 K with optimized carrier concentration. This approach highlights Cu intercalation as a readily applicable and powerful tool for maximizing the thermoelectric performance of Bi₂Te₃-based materials.