Effect of reduced Cu(InGa)(SeS)2 thickness using three-step H2Se/Ar/H2S reaction of Cu-In-Ga metal precursor

Cu(In,Ga)(Se,S)2 (CIGSS) absorbers with thicknesses from 1.9 to 0.25 µm have been grown using a three-step selenization/Ar-anneal/sulfization reaction ofCu-In-Ga metal precursors. Material characterization revealed changes in orientation, apparent grain size, and formation of voids at the Mo/CIGSS interface with reduced thickness. Even with absorber thickness decreased to 0.25 µm and lateral compositional nonuniformity, VOC and fill factor were nearly sustained, while JSC decreased due to incomplete absorption. With the 0.25-µm-thick absorber layer, an efficiency of 9.1% (without AR coating) with VOC = 612 mV, JSC = 21.0 mA/cm², and FF = 71.1% was obtained.