A solar cell includes a substrate, a protective layer located over a first surface of the substrate, a first electrode located over a second surface of the substrate, at least one p-type semiconductor absorber layer located over the first electrode, an n-type semiconductor layer located over the p-type semiconductor absorber layer, and a second electrode over the n-type semiconductor layer. The p-type semiconductor absorber layer includes a copper indium selenide (CIS) based alloy material, and the second electrode is transparent and electrically conductive. The protective layer has an emissivity greater than 0.25 at a wavelength of 2 μm, has a reactivity with a selenium-containing gas lower than that of the substrate, and may differ from the first electrode in at least one of composition, thickness, density, emissivity, conductivity or stress state. The emissivity profile of the protective layer may be uniform or non-uniform.