NOVELTY - The solar cell comprises a substrate (100), a first electrode (200) comprising a first transition metal layer and located over the substrate, a p-type semiconductor absorber layer (301) located over the first electrode, an n-type semiconductor layer (302) located over the absorber layer, a second electrode located over the n-type semiconductor layer, an alkali diffusion barrier layer (201) located between the substrate and the first transition metal layer, and a second transition metal layer (203) located between the first transition metal layer and the absorber layer.    USE - Used as a thin-film solar cell.    ADVANTAGE - The thin-film solar cell can be easily and simply manufactured with high efficiency and increased sputtering power.    DETAILED DESCRIPTION - The solar cell comprises a substrate (100), a first electrode (200) comprising a first transition metal layer and located over the substrate, a p-type semiconductor absorber layer (301) located over the first electrode, an n-type semiconductor layer (302) located over the absorber layer, a second electrode located over the n-type semiconductor layer, an alkali diffusion barrier layer (201) located between the substrate and the first transition metal layer, and a second transition metal layer (203) located between the first transition metal layer and the absorber layer. The first transition metal layer contains an alkali element or an alkali compound, and a lattice distortion element or a lattice distortion compound. The p-type semiconductor absorber layer includes a copper indium selenide based alloy material. The lattice distortion element or the lattice distortion compound has a crystal structure different from that of the first transition metal layer to distort a polycrystalline lattice of the first transition metal layer. The second transition metal layer has a higher porosity than the alkali diffusion barrier layer, and permits alkali diffusion from the first transition metal layer into the p-type semiconductor absorber layer. The alkali diffusion barrier layer has a thickness of 100-400 nm. The first transition metal layer has a thickness of 100-500 nm. The second transition metal layer has a thickness of 50-200 nm. The alkali diffusion barrier layer, the first transition metal layer and the second transition metal layer comprise 1-20 sublayers. An INDEPENDENT CLAIM is included for a method of manufacturing a solar cell.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic side cross-sectional view of a solar cell.    Substrate (100)    First electrode (200)    Alkali diffusion barrier layer (201)    Second transition metal layer (203)    P-type semiconductor absorber layer (301)    N-type semiconductor layer. (302)