Hybrid structure responsible for improved thermoelectric performance of Sn-incorporated Cu3SbSe4 with a second phase CuSe.

In this work, we design and synthesize a hybrid structure consisting of Sn-incorporated Cu₃SbSe₄ and a second phase CuSe, that is, (Cu₃Sb_{1 − x}Sn_xSe₄)(CuSe)_y (x = 0–0.04, y = 0.3–0.08), and explore the role of each phase on the improvement of the thermoelectric (TE) performance. In the Cu₃Sb_{1 − x}Sn_xSe₄ phase, the element Sn residing at the Sb site provides p-type holes while at the same time increasing the point defects and crystal structure distortion. The presence of the second phase CuSe, which is in situ formed within the Cu₃Sb_{1 − x}Sn_xSe₄ matrix, not only improves the electrical conductivity but also increases the phonon scattering on the phase boundaries. As a result, the hybrid structure allows the improvement in TE performance with the highest ZT value of 0.37 at ∼600 K for the samples at x = 0.02–0.03 and y = 0.11–0.09, which is about 42% higher than that of pristine Cu₃SbSe₄. This work reveals us a new method of improving TE performance, that is, through organizing a hybrid structure in Cu₃SbSe₄-based composites. [ABSTRACT FROM AUTHOR]