Efficiency enhancement of CIGS compound solar cell fabricated using homomorphic thin Cr2O3 diffusion barrier formed on stainless steel substrate

•A chromium oxide layer is formed as diffusion barrier by thermal oxidation process on STS substrate.•A Cr2O3 layer effectively reduces impurities diffusion into the CIGS absorber layer.•The Cr2O3 layer plays an important role in increasing the efficiency by reduction of impurity diffusion.