AlO thin films with different thicknesses were deposited by radio frequency sputtering and used as the barrier layer for flexible CIGS solar cells on stainless-steel foil. The effects of these AlO thin films on the surface roughness of stainless steel
as well as the crystalline quality
crystal structure
and photoelectric properties of the CIGS absorption layer
were investigated. Results from AFM
SEM
and XRD characterizations show that depositing AlO thin films on the stainless-steel surface significantly reduces its surface roughness
providing a smooth surface for subsequent film deposition. Moreover
it reduces the diffusion of Fe from the stainless-steel substrate into the CIGS absorption layer
leading to a noticeable improvement in the crystalline quality of the CIGS layer. Additionally
secondary ion mass spectrometry (SIMS) analysis indicates that the AlO thin films limit the Fe concentration in the CIGS absorption layer to approximately 6×10 atoms/cm. Finally
the conversion efficiency of the CIGS solar cell with a 350 nm-thick AlO barrier layer increases from 10.89% to 15.80%.
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