Synergistic Optimization of the Thermoelectric Performance of Cu₂₂Sn₁₀S₃₂ through Doping and Nanostructure Engineering

Cu22Sn10S32 thermoelectric materials show great potential among Cu-based chalcogenides due to their high power factor and environmentally friendly chemical composition. However, its ultrahigh intrinsic hole carrier concentration deteriorates the thermoelectric performance. In this work, a synergistic strategy combining doping and nanostructure engineering is proposed to optimize the thermoelectric performance of Cu22Sn10S32. On the one hand, Sb is doped into the Sn sublattice to provide donors, which compensate hole carriers and thus reduces the carrier concentration, leading to an optimized power factor. On the other hand, the composite of Cu22Sn10S32 with Sb2O5 results in the simultaneous doping of Sb elements and introduction of SnO2 nanoparticles. While maintaining the optimized electrical performance, the SnO2 nanoparticles as additional phonon scattering centers significantly lower the lattice thermal conductivity of Cu22Sn10S32, ultimately achieving a maximum zT value of 0.68 at 723 K. Our results demonstrate that cation substitutional doping and nanostructure engineering can effectively enhance the thermoelectric performance of Cu22Sn10S32.