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 degrees C and reaction for an hour, CuInSe2 nanoparticles with an average size of 6.2 nm were produced. As the reaction time was prolonged to 3 h, nanoplates appeared inside the nanoparticles. When the reaction temperature was elevated to 210 degrees C and reaction for 3 h, 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.