A Strategy for Low Thermal Conductivity and Enhanced Thermoelectric Performance in SnSe: Porous SnSe1-xSx Nanosheets

Abstract

A higher figure of merit (ZT) can be achieved for tin selenide (SnSe)-based thermoelectric materials by significantly reducing the thermal conductivity (kappa) via three promising strategies: substitution with isoelectric atoms, exfoliation of nanosheets (NSs) from a bulk ingot, and chemical transformation of the material into a porous structure. Specifically, SnSe1-xSx NSs are prepared from bulk ingots by hydrothermal Li intercalation and subsequent exfoliation. The substitution of S atoms into SnSe and the fabrication of SnSe1-xSx NSs contribute to the scattering of phonons at a number of atomic disorders and nanosized boundaries, leading to effective reduction of the lc value and an improved ZT. The introduction of porosity into the material through the chemical transformation process results in further reduction of kappa, which leads to a higher ZT. The fabricated porous SnSe0.8S0.2 NS has a maximal ZT value of 0.12 at 310 K, which is significantly higher than that of pristine SnSe.