Electrodeposition of CuInSe2 absorber layers from pH buffered and non-buffered sulfate-based solutions

CuInSe2 (CIS) thin films were deposited on Mo/glass substrates by one-step electrodeposition from aqueous baths containing CuSO4, In2(SO4)3 and SeO2 with Li2SO4 electrolyte. The quality of the electrodeposited films depended on the presence of pH buffer in the bath. CIS films deposited from non-pH buffered baths showed pronounced (112) orientation, while films exhibiting more random orientation were obtained from pH buffered baths. Denser, smoother samples were obtained from non-pH buffered baths, though with no difference in film composition. As-deposited films exhibit low crystallinity and require recrystallization by annealing in H2Se. Best devices, ∼ 9%, were obtained with CuInSe2 films deposited from non-pH buffered baths.