Enhanced thermoelectric properties of Cu₃SbSe₄-based materials by synergistic modulation of carrier concentration and phonon scattering

Cu₃SbSe₄, a copper-based sulfide free of rare earth elements, has received extensive attention in thermoelectric materials. However, its low carrier concentration restricts its widespread application. In this study, a microwave-assisted solution synthesis method was used to produce samples of Cu₃SbSe₄, which enabled the formation of CuSe in situ and increased the yield. Through the use of first-principles calculations, structural analysis, and performance evaluation, it was found that CuSe can enhance the carrier concentration and that induced nano-defects have a positive effect on reducing the lattice thermal conductivity. Moreover, doping with Sn decreases the band gap of the system and moves the Fermi level into the valence band, increasing the carrier concentration to 1.15 × 10⁻²⁰ cm⁻³. Finally, the zT value of the Cu₃Sb_0.98Sn_0.02Se₄ sample was achieved at 1.05 at 623 K when the theoretical yield of a single synthesis was 10 mmol.