The fabrication of high efficiency Cu(In,Ga)Se2 (CIGS) thin film solar cells on flexible metallic foils
generally requires the deposition of an insulating or diffusion barrier layer to reduce the diffusion of
contaminations from the metallic substrate into the CIGS absorber layer. In this work, the Al2O3 thin film is
chosen as a diffusion barrier to reduce the diffusion of Fe and other elements from the stainless steel into the
CIGS absorber during the deposition process. The substrate temperature is one the most important factors
affecting the structure and the quality of the CIGS absorber. The CIGS absorber layer is then characterized
by optical reflectance, atomic force microscopy and X-ray diffraction. The performance of the flexible CIGS
solar cells is determined from the current-voltage (I-V) measurement.