Rare earth chloride Compositing and multiscale structure lead to high thermoelectric performance in p-type Cu₃SbSe₄

Cu₃SbSe₄ is a promising Te-free p-type thermoelectric material, characterized by earth-abundant, low-cost, and environmentally friendly constituents. Nonetheless, its thermoelectric performance is poor due to its extremely low electrical conductivity (deriving from the low carrier concentration) and high lattice thermal conductivity. Herein, we report a high-performance Cu₃SbSe₄-based material by compositing LaCl3 and introducing multiscale structure. The LaCl₃-composted Cu₃SbSe₄ forms heterojunctions that facilitate charge accumulation at the interfaces. The redistribution of electrons between the two materials increases the electrical conductivity without damaging the Seebeck coefficient, and thereby significantly improving the power factor to ∼1150 μWm⁻¹K⁻² for Cu₃SbSe₄-based bulk. Furthermore, the hierarchical architecture defects are induced by LaCl₃ compositing, yielding a minimum κ_lat of ∼0.68 Wm⁻¹K⁻¹ at 673 K. As a consequence, a maximum ZT value of ∼0.90 at 673 K is achieved in the Cu₃SbSe₄ +2 mol% LaCl₃ sample, representing an 80 % improvement compared to the pristine Cu₃SbSe₄.