Synthesis and characterization of copper gallium diselenide powders prepared from the sol-gel derived precursors

Copper gallium diselenide (CuGaSe2) powders were synthesized via the sol-gel method followed by a selenization process. The sol-gel process can effectively reduce the required synthesis temperature to 400 °C due to enhanced reactivity and improved composition homogeneity. The amount of Cu2Se impurity phase was decreased when sufficient Ga3+ was added to the precursors. CuGaSe2 powders were successfully prepared when the Ga3+/Cu2+ molar ratio was increased to 2. The formation of CuGaSe2 with a pure chalcopyrite structure was confirmed via the Rietveld refinement analysis. With decreasing Ga3+/Cu2+ molar ratios, the particle size of the prepared CuGaSe2 powders was significantly enlarged because the copper selenide phase acted as a flux for the particle growth. The optical absorption spectra revealed the obtained CuGaSe2 to have a band gap of 1.68 eV. The sol-gel method combined with the selenization process was demonstrated to provide a potential approach for fabricating CuGaSe2 materials.