Unveiling the Effects\nof Spray and Selenization Process\nOptimization for Over 13% Efficient CIGSSe Solar Cells through the\nAqueous Solution Method

Cu(In,Ga)(S,Se)<sub>2</sub> (CIGSSe) solar cells were\nfabricated\nby using a spray deposition technique based on the ecofriendly aqueous\nsolution in an ambient air environment that is suitable for a low\ncost manufacturing process. The effects of spray time and postselenization\nconditions on the thin film properties and the performance of the\nCIGSSe solar cells were investigated. It was revealed that a slower\ntemperature ramping process during selenization promotes the formation\nof the larger and the denser CIGSSe grains with minimal residual oxygen\ncontent. The optimized annealing profile significantly reduces defect\ndensities and defect energies, confirmed by thermal admittance spectroscopy\n(TAS). The water-based method achieved a power conversion efficiency\n(PCE) exceeding 13% for CIGSSe solar cells, without requiring additional\ntreatment or interface modification layers.