Abstract

The formation of CuIn (Se,S)2 films for application in photovoltaic devices by post-deposition treatments of electrodeposited pre-cursors is described. The polycrystalline CuInSe₂ (CIS) pre-cursor layers were prepared by the one-step electrodeposition (ED) method on molybdenum-coated soda lime (SL) glass substrates. Growth was performed from low concentration buffered baths containing CuSO₄, In₂(SO₄)₃ and SeO₂ with Li₂SO₄ electrolyte. As deposited films were amorphous and required recrystallization by annealing in H₂Se or H₂S prior to device processing. Reaction in flowing H₂Se produced random oriented CuInSe₂ films which resulted in devices with low conversion efficiencies of only~3%. Annealing in flowing H₂S led to partial replacement of the selenium in the CuInSe₂ film with sulfur, determined by XRD and EDS to produce CuIn(Se,S)2 quaternary alloys. Devices processed from CuIn(Se,S)2 films showed improved J-V characteristic with conversion efficiencies of ~6.4%.

Key words: CuInSe2, CuIn(Se,S)2, absorber layers, electrodeposition, pHydrion buffer, photovoltaic cells.