Enhanced figure of merit for famatinite Cu3SbSe4 via band structure tuning and hierarchical architecture

The p-type Te-free Cu3SbSe4 with famatinite structure is a potential candidate for thermoelectric materials due to the low cost and eco-friendly constituent elements. However, its strong bipolar effect and high lattice thermal conductivity (κlat) are the main challenges for its performance enhancement. Herein, we report a new strategy to enhance its figure of merit zT ∼0.86 at 673 K for Cu3Sb0.95Fe0.05Se2.8S1.2 via band structure tuning and hierarchical architecture. Firstly, S substituted Se atoms in lattice can widen the band gap to alleviate the bipolar effect. Secondly, Fe doping in Sb site significantly increases the density of states, thus increasing the carrier effective mass, and obtaining a remarkably high Seebeck coefficient of ∼560 μV/K at 300 K. Moreover, the induced hierarchical architecture defects resulting in a minimum κlat of ∼0.48 W·m−1·K−1 at 673 K. Consequently, the improved Seebeck coefficient combined with low thermal conductivity leads to an enhanced zT.