Toward high efficiency and panel size 30×40 cm2 Cu(In,Ga)Se2 solar cell: Investigation of modified stacking sequences of metallic precursors and pre-annealing process without Se vapor at low temperature

Abstract Modified stacking sequence of precursors and pre-annealing process on Se vapor at low temperature were applied to Cu(In,Ga)Se 2 (CIGS) solar. The remarkable improvement of efficiency (5.53–10.10% and further 11.04%) and open circuit voltage (0.41 V–0.53 V and further 0.56 V) comes from a compact, smooth microstructure, and modified depth profile of Ga with suitable thickness of CuGa multi-stacking layers in the top of precursors as well as surface bandgap enhancement via pre-annealing process without Se vapor followed by a specific non-toxic hydrogen-assisted solid Se vapor selenization process. The effects of microstructural, compositional and electrical characteristics of Ga distribution including accumulation and interdiffusion were examined in detail. Finally, a large-area (40×30 cm 2 ) CIGS solar cell efficiency with improved open circuit voltage ( V OC ) and fill factor (FF) of 36% and 14% has been demonstrated, yielding a promising efficiency of ~11.04%.