Provided herein are methods of polishing, cleaning and texturing back contacts of thin-film solar cells. According to various embodiments, the methods involve irradiating sites on the back contact with laser beams to remove contaminants and/or smooth the surface of the back contact. The back contact, e.g., a molybdenum, copper, or niobium thin-film, is smoothed prior to deposition of the absorber and other thin-films of the photovoltaic stack. In certain embodiments, laser polishing of the back contact is used to enhance the diffusion barrier characteristics of the back contact layer, with all or a surface layer of the back contact becoming essentially amorphous. In certain embodiments, the adhesion of the absorber layer is enhanced by the textured back contact and by the presence of the amorphous metal at the deposition surface.