Remarkable electron and phonon transports in low-cost SnS: A new promising thermoelectric material

As a deceptively simple material, SnS has received extensive attention in the thermoelectric community recently due to its fascinating electron and phonon transport features, making it a very promising thermoelectric candidate. In this review, we first discuss the fundamental characteristics of SnS, including crystal structures, electronic and phononic band structures, and physical or chemical properties. Meanwhile, the approaches of improving thermoelectric performance are summarized, including simultaneous carrier concentration tuning and carrier mobility improvement, multiple valence bands transport and their synergetic optimization, and anharmonicity and phonon "softening" behavior. We also compare the difference in electrical and thermal transport properties between crystals and polycrystalline SnS. Then, theoretical calculations to predict the maximum ZT in SnS system are also established for potential performance enhancement. Finally, some future possible strategies are proposed to aim at further promoting the figure of merit of SnS. The exploration and research on this new emerged material can contribute the thermoelectrics toward practical applications to meet market demands of low-cost, high-effectiveness, and environmental compatibility.