Optimizing Thermoelectric Performance of p‐Type Polycrystalline SnS Through Low‐temperature Solid‐State Reaction

Abstract The earth‐abundant tin sulfide (SnS) has emerged as an ecologically sustainable alternative for the thermoelectric community recently. However, its wide bandgap (≈46 k B T ) is unfavorable for electrical performance, while the high vapor pressure of the S often results in a relatively low yield of synthesis. In this study, a synergistic strategy is devised to optimize the thermoelectric performance of polycrystalline SnS prepared via a low‐temperature solid‐state synthesis method. First, silver doping increases the hole carrier concentration ( n ) to ≈10 19 cm −3 . Subsequently, through selenium alloying, a dual‐effect can be achieved: the bandgap is narrowed to increase the doping efficiency, while atomic point defects are introduced to lower the thermal conductivity. Ultimately, the polycrystalline Sn 0.98 Ag 0.02 S 0.55 Se 0.45 attains a maximum ZT value of ≈0.9 at 873 K. The study indicates that promising thermoelectric performance can be obtained by a rapid synthesis method through a series of meticulously designed optimization strategies. This achievement offers novel insights and paves the way for the development of sulfide‐based thermoelectrics.