Chemical and Electrochemical Processing of High Quality CIS/CIGS Absorber, Buffer, Window, and Anti-Reflective Coating for Low Cost Photovoltaic Technology

Abstract

Overall application of inexpensive, non-vacuum chemical (CBD) and electrochemical deposition (ECD) techniques that can be scaled-up to industrial processes is targeted for processing the absorber-, buffer-, and window-layer of CISe/CIGSe TFSCs to overcome current process incompatibilities mainly resulting from the simultaneous use of moderate temperature non-vacuum (50-70C) and high temperature (500-700C) vacuum processes. Low cost ECD processing of ternary CuInSe2 and quaternary Cu(In,Ga)Se2 chalcopyrite semiconductor films with crystal quality similar to that of PVD grown films was achieved by as few as possible process steps skipping selenization at elevated temperatures. Chalcopyrite phase formation was confirmed already in as-deposited films. The film quality was further improved by subsequent annealing at 300C, for 2h, in N2. ZnSe bufferand ZnO window-layers were processed by CBD and ECD techniques, respectively. The properties of n-ZnO/i-ZnO bilayer were thoroughly investigated with respect to layer thickness and dopant concentration. By successive integration of low cost ECD ZnO/CBD ZnSe buffer and window components in CISe/CIGSe solar cells with absorbers grown by standard vacuum techniques, the respective p-n junctions exhibited I-V characteristics competing with monocrystalline silicon(c-Si) I-V.