Selenization of Cu2ZnSn(S,Se)4 thin-films with varied pressures

•Adjusting nitrogen pressure during annealing improves delamination of CZTSSe absorption layer.•Selenization under varying pressure reduces the thickness of fine crystal layers in CZTSSe films.•Different pressures during selenization can help CZTSSe formation in the low temperature region (∼350 °C)•The CZTSSe cell with 10.4% efficiency was prepared by different pressure selenization with 35% improvement.