Fabrication of CuInSe 2 films and solar cells by the sequential evaporation of In 2Se 3 and Cu 2Se binary compounds

Abstract

Cu 2Se/In x Se( x≈1) double layers were prepared by sequentially evaporating In 2Se 3 and Cu 2Se binary compounds at room temperature on glass or Mo-coated glass substrates and CuInSe 2 films were formed by annealing them in a Se atmosphere at 550°C in the same vacuum chamber. The In x Se thickness was fixed at 1 μm and the Cu 2Se thickness was varied from 0.2 to 0.5 μm. The CuInSe 2 films were single phase and the compositions were Cu-rich when the Cu 2Se thickness was above 0.35 μm. And then, a thin CuIn 3Se 5 layer was formed on the top of the CuInSe 2 film by co-evaporating In 2Se 3 and Se at 550°C. When the thickness of CuIn 3Se 5 layer was about 150 nm, the CuInSe 2 cell showed the active area efficiency of 5.4% with V oc=286 mV, J sc=36 mA/cm 2 and FF=0.52. As the CuIn 3Se 5 thickness increased further, the efficiency decreased.