A method for manufacturing a CIGS thin film photovoltaic device includes forming a back contact layer on a substrate, forming an Se-rich layer on the back contact layer, forming a precursor layer on the Se-rich layer by depositing copper, gallium and indium resulting in a first interim structure, annealing or selenizing the first interim structure, thereby forming Cu/Se, Ga/Se or CIGS compounds along the interface between the back contact layer and the precursor layer and resulting in a second interim structure, and selenizing the second interim structure, thereby converting the precursor layer into a CIGS absorber layer on the back contact layer.