Transparent Wide-Gap Chalcopyrite CuGaSe2 Thin-Film Photovoltaics with Noble Dot-Patterned Mo p-Electrode

Wide-gap chalcopyrite CuGaSe₂ thin-film photovoltaics are fabricated on a noble dot-patterned Mo p-electrode for use as the top cell in high-efficiency tandem photovoltaics. Device characteristics of these CuGaSe₂ cells are compared with those of cells directly formed on a transparent conductive oxide film. The Mo-dot p-electrode enables high-temperature deposition of the CuGaSe₂ thin film, and the maximum efficiency increased by about 1 percentage point due to improvements in open-circuit voltage and fill factor. The microscopic interfacial structure between CuGaSe₂ and the Mo-dot p-electrode is investigated using transmission electron microscopy.