Controlled synthesis of luminescent CuInS2 nanocrystals and their optical properties

Luminescent CuInS2 nanocrystals have been synthesized in dodecanethiol using air-stable precursors. The nanocrystals were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Raman spectroscopy. The optical properties of the CuInS2 nanocrystals can be controlled by changing the reaction conditions, such as reaction time, temperature, and addition of ligands. It was found that the steady-state photoluminescence spectrum of the close-packed CuInS2 nanocrystals on glass substrate peaked at longer wavelength than that of the colloidal ones and the close-packed nanocrystals possessed a shorter luminescence decay time. This behavior was explained on the basis of Förster resonant energy transfer due to the shorter distance between nanocrystals on substrate.