Synthesis and Characterization of Cu x (In, Ga) y Se z Nanoparticles by Colloidal Route

The quarternary CIGS nanoparticles for absorber layer of solar cells have been synthesized with various mole ratios by colloidal route. The CIGS nanoparticles were prepared by reacting CuI, InI3, GaI3 in pyridine with Na2Se in methanol at 0°C under inert atmosphere. For Cu0.9In0.8Ga0.3Se2 and Cu0.9In0.7Ga0.4Se2 stoichiometric ratios, tube-type nanofibers were obtained with the widths in the range of 20–50 nm and lengths of 0.1–3 μm from reaction at 0°C for 20 min. For Cu1.1In0.68Ga0.23Se1.91, and Cu0.9In0.68Ga0.23Se1.91 ratios, spherical nanoparticles were obtained from the same reaction condition. As compared to particles from Cu0.9In0.68Ga0.23Se1.91 ratio, more uniform and smaller nanoparticles with diameter in the range of 5–20 nm were obtained from the Cu1.1In0.68Ga0.23Se1.91 stoichiometric ratio. The morphology change of the CIGS particles seems to be closely related to the ratio of Cu/(In, Ga).