Scalable synthesis and enhanced thermoelectric properties of Cu-doped and Se-substituted Bi₂Te₃-based materials via high-pressure sintering

This study demonstrates a scalable approach for synthesizing Bi₂Te_3-xSe_xCu_y (x = 0.4–0.8; y = 0–0.02) through Cu doping and Se substitution, using high-pressure hot-press sintering to mitigate performance degradation in large-scale production. Raw materials were processed in 200 g batches, melted, and sintered into 50 mm diameter disks under 200 MPa pressure. Cu doping decreased carrier concentration and electrical conductivity, but the enhanced Seebeck coefficient significantly improved the power factor. Furthermore, Se substitution optimized carrier concentration and increased phonon scattering, reducing lattice thermal conductivity. The optimized Bi₂Te_2.3Se_0.7Cu_0.02 sample achieved a peak ZT of 0.82 at 423 K, representing a 50 % improvement over pristine (x = 0.4, y = 0) sample. This work underscores the potential of combining doping, substitution, and high-pressure processing for high-performance thermoelectric materials in scalable applications.