Preparation and characterization of Cu(In, Ga)Se2 powders via the modified solvothermal route

Cu(In, Ga)Se2 powders were successfully prepared in the solvothermal reaction at 240 °C via using triethanolamine in the solution. The Raman spectrum and the UV–Vis-NIR spectroscopy further confirmed that the obtained powders were single-phased Cu(In, Ga)Se2 compound. In comparison with the conventionally solvothermal process, the required reaction duration was significantly reduced to 5 h as the concentration of triethanolamine was 2 M. Triethanolamine induces the two-dimensional growth of Cu(In, Ga)Se2 crystals via the selective passivation, leading to the formation of plate-like particles at high concentrations of triethanolamine. The photoluminescence spectra implied that the number of surface defects was reduced via capping the nonradiative recombination centers with triethanolamine. Ethylenediamine played a similar role to triethanolamine, facilitating the synthesis of Cu(In, Ga)Se2. In the solvothermal process, increasing the reaction duration reduced the amount of CuInSe2 and CuGaSe2, resulting in the formation of pure Cu(In, Ga)Se2 powders.