Realizing the Ultralow Lattice Thermal Conductivity of Cu(3)SbSe(4) Compound via Sulfur Alloying Effect

Cu(3)SbSe(4) is a potential p-type thermoelectric material, distinguished by its earth-abundant, inexpensive, innocuous, and environmentally friendly components. Nonetheless, the thermoelectric performance is poor and remains subpar. Herein, the electrical and thermal transport properties of Cu(3)SbSe(4) were synergistically optimized by S alloying. Firstly, S alloying widened the band gap, effectively alleviating the bipolar effect. Additionally, the substitution of S in the lattice significantly increased the carrier effective mass, leading to a large Seebeck coefficient of ~730 μVK(−1). Moreover, S alloying yielded point defect and Umklapp scattering to significantly depress the lattice thermal conductivity, and thus brought about an ultralow κ(lat) ~0.50 Wm(−1)K(−1) at 673 K in the solid solution. Consequently, multiple effects induced by S alloying enhanced the thermoelectric performance of the Cu(3)SbSe(4)-Cu(3)SbS(4) solid solution, resulting in a maximum ZT value of ~0.72 at 673 K for the Cu(3)SbSe(2.8)S(1.2) sample, which was ~44% higher than that of pristine Cu(3)SbSe(4). This work offers direction on improving the comprehensive TE in solid solutions via elemental alloying.