Characterization of the Cu(In,Ga)Se2/Mo interface in CIGS solar cells

In a high efficiency CIGS solar cell, we observed a MoSe2, layer at the interface by SIMS, TEM and X-ray diffraction, MoSe2, had a layer structure and the layers were oriented perpendicular to the Mo layer. The MoSe2, contributes to the improvement of adhesion at the CIGS/Mo interface. The effects of the MoSe2, layer on the electrical and photovoltaic properties of CIGS solar cells were investigated. The CIGS/Mo heterocontact, including the MoSe2, layer, is not Schottky-type, but a favorable ohmic-type by the evaluation of dark I-V measurement at low temperature. A characteristic peak at 870 nm is observed in the differential quantum efficiency of a solar cell with a CIGS thickness of 500 nm. This peak relates to the absorption of the MoSe2 layer. The band gap of MoSe2, is calculated to be 1.41 eV from the absorption peak. (C) 2001 Elsevier Science S.V. All rights reserved.