Growth of Zn doped Cu(In, Ga)Se2 thin films by RF sputtering for solar cell applications

Cu(In, Ga)Se2 (CIGS) surface was modified with Zn doping using a magnetron sputtering method. CuInGa:Zn precursor films targeting a CuIn0.7Ga0.3Se2 stoichiometry with increasing Zn content from 0 to 0.8 at% were prepared onto Mo-coated glass substrates via co-sputtering of Cu–Ga alloy, In and Zn targets. The CuInGa:Zn precursors were then selenized with solid Se pellets. The structures and morphologies of grown Zn doped CIGS films were found to depend on the Zn content. At zinc doping level ranging between 0.2 and 0.6 at%, the Zn doping improved the crystallinity and surface morphology of CIGS films. Compared with the performance of the non-doped CIGS cell, the fabricated CIGS solar cell displayed a relative efficiency enhancement of 9–22% and the maximum enhancement was obtained at a Zn content of 0.4 at%.

► Zn doped CIGS films were prepared by co-sputtering.
► The Zn doping method improves the crystallinity of CIGS absorber layers.
► Zn doping promotes improvements in CIGS absorber surface morphology.
► The optimized solar cell is obtained at a Zn content of 0.4 mol%.
► The Zn doping enhances the performance of cells with a percentage up to 22%.