Room-temperature FeSi₂-doped Cu₂Se thermoelectric films with enhanced figure of merit

Thermoelectric (TE) materials offer a promising pathway toward achieving carbon neutrality by converting waste heat into electricity. The enhancement of their figure-of-merit (zT) depends on optimizing the composition of materials and nanostructures, reducing the thermal conductivity, and increasing the power factor. Cu₂Se, a superionic material, achieves a zT of 0.4 at 300 K by facilitating Cu ion movement within its face-centered cubic lattice, effectively suppressing thermal conductivity. Herein, we present a novel TE material developed by doping Cu_xSe crystals of different compositions with FeSi₂. We report a remarkable zT of 0.69 at 298 K for Cu₂Se-based materials and reveal the presence of the CuO and Cu₂O tiny crystals on the material surface, uniform dispersion of Si within the film, and formation of distinctive amorphous FeO. Our strategy holds great potential for notably advancing waste heat recovery in sustainable TE materials.