Solution-Synthesized In4SnSe4 Semiconductor Microwires with a Direct Band Gap

Semiconductor materials having direct band gaps that overlap well with the solar spectrum are important for a variety of applications in solar energy conversion and optoelectronics. Here, we identify the ternary chalcogenide In4SnSe4 as a direct band gap semiconductor having a band gap of approximately 1.6 eV. In4SnSe4, which contains isolated tetrahedral [SnIn4]8+ clusters embedded in an In–Se framework, was synthesized by precipitation from solution at 300 °C. The In4SnSe4 product consists of microwires having lengths of approximately 5–20 μm and widths of approximately 100–400 nm. Band structure calculations predict a direct electronic band gap of approximately 2.0 eV. Diffuse reflectance UV–visible spectroscopy qualitatively validates the predicted direct band gap, yielding an observed optical band gap of 1.6 eV.