Size-controlled chalcopyrite CuInS2 nanocrystals: One-pot synthesis and optical characterization

Chalcopyrite ternary CuInS2 semiconductor nanocrystals have been synthesized via a facile one-pot chemical approach by using oleylamine and oleic acid as solvents. The as-prepared CuInS2 nanocrystals have been characterized by instrumental analyses such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM)/high-resolution TEM (HRTEM), energy-dispersive X-ray spectroscopy (EDS), UV-vis absorption spectroscopy (UV-vis) and photoluminescence (PL) spectroscopy. The particle sizes of the CuInS2 nanocrystals could be tuned from 2 to 10 nm by simply varying reaction conditions. Oleylamine, which acted as both a reductant and an effective capping agent, plays an important role in the size-controlled synthesis of CuInS2 nanocrystals. Based on a series of comparative experiments under different reaction conditions, the probable formation mechanism of CuInS2 nanocrystals has been proposed. Furthermore, the UV-vis absorption and PL emission spectra of the chalcopyrite CuInS2 nanocrystals have been found to be adjustable in the range of 527-815 nm and 625-800 nm, respectively, indicating their potential application in photovoltaic devices.