Investigation of Some Transparent Metal Oxides as Damp Heat Protective Coating for CIGS Solar Cells.

摘要

We investigated the protective effectiveness of some transparent metal oxides (TMO) on CIGS solar cell coupons against damp heat (DH) exposure at 85 deg C and 85% relative humidity (RH). Sputter-deposited bilayer ZnO (BZO) with up to 0.5-ium Al-doped ZnO (AZO) layer and 0.2-ium bilayer InZnO were used as inherent part of device structure on CdS/CIGS/Mo/SLG. Sputter-deposited 0.2-ium ZnSnO and atomic layer deposited (ALD) 0.1-ium Al2O3 were used as overcoat on typical BZO/CdS/CIGS/Mo/SLG solar cells. The results were all negative--all TMO-coated CIGS cells exhibited substantial degradation in DH. Combining the optical photographs, PL and EL imaging, SEM surface micro-morphology, coupled with XRD, I-V and QE measurements, the causes of the device degradations are attributed to hydrolytic corrosion, flaking, micro-cracking, and delamination induced by the DH moisture. Mechanical stress and decrease in crystallinity (grain size effect) could be additional degrading factors for thicker AZO grown on CdS/CIGS.