In this paper, we numerically investigated the effect of Bismuth iodide (BiI3) interfacial layer with different hole transport layer (HTL) candidates (including Spiro - OMeTAD, Cu2O, CuI, CuAlO2, CuSbS2, SrCu2O2, CuSCN, PTAA, P3HT) in FAPI based perovskite (i.e., FA(0.85)Cs(0.15)Pb((I0.085Br0.15)(3)) solar cells using Solar cell simulator capacitance software (SCAPS-1D). Our results reveal that the addition of a thin BiI3 layer at the interface between the Perovskite active layer and the HTL efficiently improves hole extraction by defect passivation (i. e., reducing charge recombination and ion migration), which in turn enhances device performance compared to a typical reference architecture. The final optimized device photovoltaic parameters with interfacial layer confirm that the Cu-based HTL's, especially Cu2O(PCE = 24.07%), and SrCu2O2 (PCE = 23.91%) HTL's are more suitable for the FA(0.85)Cs(0.15)Pb(I0.85Br0.15)(3) solar cells than other HTL alternatives, including Spiro - OMeTAD due to higher hole mobility and the valence-band offset alignment between Perovskite/HTL interface. Also, the influence of several metal electrodes (Ag, Cr, Cu, Au, Ni, Pt) is carefully studied with and without the BiI3 interlayer. It is demonstrated that the energy band misalignment between the HTL and the metallic top electrode restricts charge collection, which is directly associated with low work functions. As a consequence, high work function electrodes such as Au, Ni, and Pt have to be preferred in the presence or absence of the interlayer. The last section addresses the influence of the active layer, BiI3 interlayer thicknesses on device performance and also the effect of parasitic resistances (R-series and R-shunt) were studied. From this analysis, BiI3 interfacial layer seems highly beneficial for improving the performance of experimental perovskite solar cells.