Facile Preparation of Wurtzite CuInE₂ (E = S, Se) Nanoparticles Under Solvothermal Conditions

In this work, the synthesis of nanoscale CuInS₂ and CuInSe₂ was developed using molecular precursors of the type [(Ph₃P)₂CuIn(ER)₄] (E = S, Se) and solvothermal reactions. Various conditions were investigated including the use of different precursors, reaction temperatures, reaction times and the addition of a secondary chalcogen source to mixtures. After optimizing conditions, nanoparticles of CuInS₂ and CuInSe₂ were isolated with controlled sizes in the range of 2-5 nm (wurtzite structure), which ultimately tuned the band gap energies of the materials. Characterization methods including powder X-ray diffraction, electron microscopy, and optical spectroscopy were used to investigate their structures and photophysical properties.