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

在低载流子浓度的n型层状SnS晶体中实现高的面内热电性能

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.

硫化锡(SnS)作为一种简单的二元化合物,具有优异的电子和声子输运特性,加上其成本低、地球储量丰富、环境友好等优点,在热电材料领域显示出巨大的竞争力.为了促进低成本热电器件的发展和应用,我们采用溴(Br)掺杂生长SnS晶体实现其从本征p型向n型的转变.此外,得益于低的载流子浓度,我们报道了n型SnS优异的面内载流子迁移率和较大的塞贝克系数,从而导致一个高的功率因子PF~28μW cm^(-1)K^(-2).弹性性能计算表明, SnS中的低晶格热导率与其强非简谐性密切相关.结合其优良的热电输运性能,在室温下ZT值达到了~0.4, 823 K时其理论热电转化效率达到~5%.