Abstract MAPbI3 perovskite-based solar cell (PSC) has received widespread attention in later years due to its high absorption. However, the top flat electrode affects badly the light received to the absorber layer with reduced efficiency. In this paper, the influence of texturing the top FTO electrode surface with a triangular saw-tooth grating on both the optical and electrical performance of the studied PSC is studied. Interference effects are considered by modeling the PSC structure as a Fabry–Perot resonator. In this regard, the finite difference time domain method is utilized to precisely simulate the optical characteristics of the nano-structural design. The geometrical parameters of the triangular grating (TG) are optically studied to maximize the light absorption. Furthermore, the effect of absorber thickness on the optoelectronic performance is investigated. To estimate the conversion efficiency (η) of the reported PSC structure, the bulk and Langevin recombination mechanisms are taking into account. The proposed grating enhances the light coupling and hence the light absorption and the generated current density are enlarged. At the absorber thickness of 350 nm, maximum η of 19.5 % is achieved for the proposed TG structure with an enhancement of 19.6% compared to the structure with flat FTO layer. Accordingly, the simulation results could be useful for further understanding and improving the physical behavior of MAPbI3 based PSC.