Green synthesis of tunable Cu(In1-xGax)Se-2 nanoparticles using non-organic solvents

A green synthesis route of Cu(In1-xGax)Se-2 nanoparticles with variable Ga content is described in this report for the first time. Only water and a minimum amount of energy input are used. Heating appropriate amounts of Cu, In, Ga and Se dispersed in an aqueous solution containing mercapto-acetic acid in a microwave oven gives rise to small and uniform nanoparticles. These new materials have been characterized to confirm composition, geometrical and structural properties. Transmission electron microcopy (TEM) confirmed size distribution around 4 nm. XRD confirmed the chalcopyrite structure with an average crystallite size of 3 nm. Atomic concentration and oxidation states of the different elements have been investigated using X-ray photoelectron spectroscopy (XPS). UV-visible absorption characterization confirmed the tunable optical properties of these materials. The proposed synthesis is scalable for commercial production with minimal environmental impact.