Abstract:A CuIn1-xGaxSe2 (CIGS) thin film solar cell model with MoSe2 transition layer was established, using SCAPS-1D software. The influence of MoSe2 interface layer formed between absorption layer CIGS and the back contact Mo on the solar cell performance was investigated.By changing the doping concentration,thickness and bandgap of MoSe2 layer, it is found that the MoSe2 and the variation of parameters have a significant effect on the electrical characteristics and photovoltaic parameters of CIGS thin film solar cells. Based on the energy band, the interfaces of Mo/MoSe2 and MoSe2/CIGS are analyzed. It is considered that Mo/MoSe2 is a Schottky contact, MoSe2/CIGS is an ohmic contact. When suitable parameters of MoSe2 layer are formed into the interface, it will provide a new path for designing CIGS solar cells with thinner absorption layer.