Topotactic anion-exchange in thermoelectric nanostructured layered tin chalcogenides with reduced selenium content.

Anion exchange has been performed with nanoplates of tin sulfide (SnS) via "soft chemical" organic-free solution syntheses to yield layered pseudo-ternary tin chalcogenides on a 10 g-scale. SnS undergoes a topotactic transformation to form a series of S-substituted tin selenide (SnSe) nano/micro-plates with tuneable chalcogenide composition. SnS0.1Se0.9 nanoplates were spark plasma sintered into phase-pure, textured, dense pellets, the ZT of which has been significantly enhanced to ≈1.16 from ≈0.74 at 923 K via microstructure texturing control. These approaches provide versatile, scalable and low-cost routes to p-type layered tin chalcogenides with controllable composition and competitive thermoelectric performance.