Fabrication of CuInSe2 films and solar cells by the sequential evaporation of In2Se3 and Cu2Se binary compounds

Cu2Se/InxSe(x approximate to 1) double layers were prepared by sequentially evaporating In2Se3 and Cu,Se binary compounds at room temperature on glass or Mo-coated glass substrates and CuInSe2 films were formed by annealing them in a Se atmosphere at 550 degreesC in the same vacuum chamber. The InxSe thickness was fixed at 1 mum and the Cu2Se thickness was varied from 0.2 to 0.5 mum. The CuInSe2 films were single phase and the compositions were Cu-rich when the Cu, Se thickness was above 0.35 mum. And then, a thin CuIn3Se5 layer was formed on the top of the CuInSe2 film by co-evaporating In2Se3 and Se at 550 degreesC. When the thickness of CuIn3Se5 layer was about 150nm. the CuInSe2 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 CuIn3Se5 thickness increased further, the efficiency decreased. (C) 2001 Elsevier Science B.V. All rights reserved.