Low carrier concentration leads to high in-plane thermoelectric performance in n-type SnS crystals

As a simple binary compound, p-type SnS shows great competitiveness in thermoelectrics due to the certain appealing carrier and phonon transport behaviors, coupled with its cost-effectiveness, earth-abundance and environmental compatibility. To promote the application of low-cost thermoelectric devices, we synthesized n-type SnS crystals through bromine doping. Herein, we report a high in-plane power factor of ∼28 µW cm−1 K−2, and attribute it to an outstanding in-plane carrier mobility in the crystal form and the large Seebeck coefficient benefitting from the low carrier concentration. The calculations of elastic properties show that the low lattice thermal conductivity in SnS is closely related to its strong anharmonicity. Combining the excellent electrical transport properties with low thermal conductivity, a final ZT of ∼0.4 is attained at 300 K, projecting a conversion efficiency of ∼5% at 873 K along the in-plane direction.