Abstract In this paper, a series of recombination paths in Al:ZnO/ZnO/CdS/Cu(In,Ga)Se2 (CIGS) solar cell has been carried out through photoluminescence (PL) emission, optoelectronic conversion characteristic and AFORS HET simulation. Proper rapid thermal annealing (RTA) lead to the improvement of CIGS performance by reducing bulk recombination of CIGS layer and interface recombination, which opens the way to explore a useful method to significantly ameliorate the microstructure within the CIGS layer. A maximum value for the conversion efficiency was obtained when the annealing temperature was continuously increased to 400 °C, where the efficiency increased by 43%, and the recombination from the interface states, the bulk defect traps and the tunneling enhancement recombination was reduced to the lowest. The opto-electronic parameters, such as short-circuit current Jsc, open-circuit voltage Voc, reverse saturation current J0 and the series resistance Rs have been correlatively investigated to the nonradiative transition among the various defects and are strongly dependent upon the annealing temperature as well.