Point Defect Engineering Advances Thermoelectric SnS Crystals

The pursuit of low-cost, high-performance thermoelectric materials is a fundamental challenge in thermoelectric research and its applications, as it can realize the direct thermal to electrical energy conversion. In the past decade, with the emergence of the hot-spot SnSe thermoelectric material, the homologous SnS has gradually gained wide attention as its lower cost and higher abundance of S. However, the highly electronegative (ionic) nature of S and the large bandgap (~ 1.2eV) in SnS cause inherently poor electrical transport. Additionally, grain boundary in the polycrystals brings about complex defects and which further deteriorates the performance. The behavior of defects in polycrystalline SnS is difficult to clarify and modulate, but higher carrier mobility and the only point defects are considered in the crystals where factors with less influence make the identification and optimization of the transport mechanism easier. Based on it, this article proposes the improvement strategy of thermoelectric performance in SnS crystals enabled by the point defect engineering.