In the recent two decades, CdTe thin-film solar cells have been used due to their proper efficiency and low manufacturing cost. The transparent conducting oxide (TCO) applied in front of them has an important role in improving performance both optically and electrically. In this paper, we have used molybdenum trioxide (MoO3) as a TCO layer, and we also have done a comparison between this and other common TCO layers such as tin oxide (SnO2), zinc oxide (ZnO) and titanium dioxide (ZnO) and then examined solar cell parameters in each structure. Numerical simulations of aforesaid CdTe solar cell structures have been done employing SCAPS software. Results indicate the electrical and optical parameters of CdTe/CdS solar cell with a MoO3 TCO layer which has been improved compared with other structures so that the efficiency of it reaches to 14.72% .This value is 0.64%, 0.51%, and 0.1% higher than similar cells with transparent oxide layer SnO2, TiO2, and ZnO, respectively. پرونده مقاله