Comparison of Cell Performance of ZnS(O,OH)/CIGS Solar Cells With UV-Assisted MOCVD-ZnO:B and Sputter-Deposited ZnO:Al Window Layers

ZnO:B films deposited by ultraviolet light-assisted metal-organic chemical vapor deposition (UM-ZnO:B) were applied to CBD-ZnS(O,OH)/CIGS solar cells in order to eliminate plasma damages during the subsequent ZnO sputtering. It was verified that the conversion efficiency of CIGS solar cells with a UM-ZnO:B window layer was higher than that of the device with a sputter-deposited(Sp-) ZnO:Al window layer; in both cases, thick (120 nm) and thin (10 nm) ZnS(O,OH) buffer layers were used. The conversion efficiency of a CIGS solar cell was improved from 16.3% to 17.5% upon replacement of the Sp-ZnO:Al by a UM-ZnO:B window layer when the thick ZnS(O,OH) (120 nm) buffer layer was used. Notably, the conversion efficiency was remarkably improved from 0.2% to 15.6% by the replacement of the window layer even when the ultrathin ZnS(O,OH) (10 nm) buffer layer was used. The temperature dependence of open-circuit voltage revealed that interface recombination decreased owing to the use of a UM-ZnO:B window layer.