Microwave synthesis of microstructured and nanostructured metal chalcogenides from elemental precursors in phosphonium ionic liquids.

We describe a general approach for the synthesis of micro-/nanostructured metal chalcogenides from elemental precursors. The excellent solubility of sulfur, selenium, and tellurium in phosphonium ionic liquids promotes fast reactions between chalcogens and various metal powders upon microwave heating, giving crystalline products. This approach is green, universal, and scalable.

Hot carrier filtering in solution processed heterostructures: a paradigm for improving thermoelectric efficiency.

An approach based on a solution-based synthesis that produces a thermally stable Ag/oxide/S2 Te3 -Te metal-semiconductor heterostructure is described. With this approach, a figure of merit of zT = 1.0 at 460 K is achieved, a record for a heterostructured material made using wet chemistry. Combining experiments and theory shows that the large increase in the material's Seebeck coefficient results from hot carrier filtering.

Silver-based intermetallic heterostructures in Sb2Te3 thick films with enhanced thermoelectric power factors.

In this work, Ag(x)Te(y)-Sb(2)Te(3) heterostructured films are prepared by ligand exchange using hydrazine soluble metal chalcogenide. Because of the created interfacial barrier, cold carriers are more strongly scattered than hot ones and thereby an over 50% enhanced thermoelectric power factor (~2 µW/(cm·K(2))) is obtained at 150 °C. This shows the possibility of engineering multiphases to further improve thermoelectric performance beyond phonon scattering through a low-temperature solution processed route.