A facile route for synthesis of CuInxGa1−xSe2 nanocrystals with tunable composition for photovoltaic application

A facile colloidal synthesis of CuInxGa1−xSe2 (CIGS) nanocrystals was successfully performed using a simple heating method. These nanocrystals were prepared by employing glycerol as a main solvent and oleylamine (OLA) as a complexing agent. X-ray diffraction showed that CuInSe2 with a chalcopyrite structure was formed by using a volume content of OLA as small as ~30 %. No variation was found in the compound phase between samples synthesized in a mixed solvent with 30 % OLA and in 100 % OLA-added solvent. Transmission election microscopy confirmed the crystal structure and showed a particle sizes below 20 nm. Energy-dispersive X-ray analysis (EDS) confirmed the chemical composition of these samples. And UV–Vis spectroscopy investigated the band gap of CIGS nanoinks. Furthermore, we used this method to prepare CIGS nanocrystals with different band gap energies by varying the In/Ga ratio of the reactants. Therefore, this green and economic route proposed has the potential for large-scale synthesis of CIGS nanocrystals, which is beneficial to low-cost photovoltaic application. XRD patterns and TEM images of CuInSe2 nanocrystals, obtained for samples synthesized with pure OLA and with mixed solvent.