Strategy to optimize the overall thermoelectric properties of SnTe via compositing with its property-counter CuInTe2

SnTe, a lead-free analogue of PbTe, exhibits inferior thermoelectric performance due to its intrinsically high carrier concentration, and thus too low Seebeck coefficient and high thermal conductivity. To optimize the overall properties of SnTe, we composited SnTe with the other compound with opposite performance. CuInTe₂ is a good choice due to its low carrier concentration, high Seebeck coefficient and relatively low thermal conductivity. As a result, the most optimized properties can be obtained in CuSn_mInTe_m+2 when m = 7, and an enhanced figure of merit ZT can be obtained, ∼1.0 at 873 K, which is a three-fold increase for pure CuInTe₂ and one-fold increase for pure SnTe. The overall properties are optimized much greater than the expectation, which was estimated through Effective Medium Theory (EMT). Such deviation can be ascribed to the existence of high density of coherent nanostructures.