Phase composition of CuInSe2 in different annealing process

CuInSe2 was synthesized by a low cost, non-vacuum hydrothermal solution method using copper chloride, indium chloride and Se powder as raw materials. The reaction schemes of CuInSe2 in different annealing processes were investigated by in-situ X-ray diffraction measurements. Its phase composition, crystal structure and morphology properties of CuInSe2 were studied. The results show that CuInSe2 has chalcopyrite crystal structure and it remains stable below the temperature of 773 K, but it decomposes to CuSe and InSe at temperature above 773 K in vacuum annealing. While in oxygen annealing, CuInSe2 is oxidized to CuO, In2O3 and SeO2 at the temperature of 523 K. Therefore, the temperature of selenization or annealing must be lower than 773 K in order to reduce the amount of CuSe and InSe in large production scale. The results were demonstrated by energy dispersive spectrometer as well. The process of its reaction mechanism was discussed based on the experimental data.