Toward high efficiency and panel size 30 x 40 cm(2) Cu(I,Ga)Se-2 solar cell: Investigation of modified stacking sequences of metallic precursors and pre-annealing process without Se vapor at low temperature

Modified stacking sequence of precursors and pre-annealing process on Se vapor at low temperature were applied to Cu(ln,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-nnealing 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 x 30 cm(2)) CIGS solar cell efficiency with improved open circuit voltage (V-OC) and fill factor (FE) of 36% and 14% has been demonstrated, yielding a promising efficiency of similar to 11.04%. (C) 2014 Elsevier Ltd. All rights reserved.