A facile route to synthesize chalcopyrite CuInSe₂ nanocrystals in non-coordinating solvent

A facile route for synthesizing CuInSe₂ nanocrystals was developed using an alkanethiol as ligand and noncoordinating octadecene as solvent. The CuInSe₂ nanoparticles and nanoplates were obtained, depending on the reaction temperature and time. When the reaction temperature was set at 180 °C and reaction for an hour, CuInSe₂ nanoparticles with an average size of 6.2nm were produced. As the reaction time was prolonged to 3h, nanoplates appeared inside the nanoparticles. When the reaction temperature was elevated to 210 °C and reaction for 3h, triangular or hexagonal CuInSe₂ nanoplates with sharp edges were synthesized. It was proposed that the Ostwald ripening induced the morphology evolution of the CuInSe₂ nanoparticles into nanoplates at the higher temperature. The nanoparticles and nanoplates were characterized by transmission electron microscopy (TEM), selected area electron diffraction (SAED), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). The UV-vis absorption spectra of the CuInSe₂ nanoparticles were significantly blue-shifted in comparison with the bulk material due to the quantum confinement.