Luminescence down shifting (LDS) is an elegant approach used to improve the efficiency of single solar cells, in this approach, the photovoltaic (PV) glass material is replaced with a thin layer of polymer polymethyl methacrylate (PMMA) doped with optically active organic dyes. In this paper, we present a theoretical study. To assess the improvements introduced by LDS on an n-i-p-GaAs solar cells structure formed by diverse types of windows layers (Al0.8Ga0.2As, Al0.52In0.48P, and Ga0.5In0.5P). The performance of the solar cell is investigated as a function of organic dyes. It has been shown that the gain in power conversion efficiency attains values up to 5.79, 8.15, and 8.37% with Al0.8Ga0.2As, Al0.52In0.48P, and Ga0.5In0.5P in the standard spectrum AM1.5G, moreover, they increase the short circuit current density.