Comparative study of densification techniques for tailoring the thermoelectric behavior of Bi2Se3

Bismuth selenide (Bi₂Se₃), a layered chalcogenide, is a promising thermoelectric material whose performance is strongly influenced by the densification method. In this study, nanostructured Bi₂Se₃ was synthesized and consolidated using cold pressing, hot pressing, and spark plasma sintering methods. The structural, electrical, and thermal transport properties of the samples were systematically evaluated. Temperature-dependent Hall measurements provided insight into carrier concentration and mobility. The hot-pressed sample exhibited the highest mobility of 576 cm²/V s, which is ~ 41 and 51% higher than that of the cold-pressed and spark plasma sintered samples, attributed to an increased mean free path. The temperature-dependent electrical conductivity and Seebeck coefficient were analyzed, revealing a maximum power factor of 552.7 μW/mK² at 550 K for the hot-pressed sample. A low total thermal conductivity of 0.51 W/mK at 403 K was observed for the cold-pressed Bi₂Se₃ sample. Acoustic phonon scattering was indicated by weighted mobility fitting, which yielded temperature dependencies of T^−1.31 and T⁻¹ for the cold-pressed and hot-pressed samples. Our findings suggest that the hot-pressed Bi₂Se₃ sample exhibited an improved thermoelectric figure of merit (zT) of 0.18 at 510 K.