<p>This study presents a significant enhancement in the efficiency of inverted tandem solar cells through the integration of titanium dioxide (TiO₂) nanostructure reflectors using the Finite Element Method (FEM). Introducing TiO₂ nanostructures boosts absorption by increasing reflection and optimizes carrier transport by extending the transmission path. The top cell utilizes a perovskite layer (CH₃NH₃PbI₃) as the active layer, with a light absorption range of 300 to 800 nm. The bottom cell incorporates TiO₂ nanostructures, which serve dual roles as an electron transport layer (ETL) and a reflector, combined with an active molybdenum ditelluride (MoTe₂) layer. This system demonstrated an expanded input power absorption range up to 1200 nm, leading to a 4.77% improvement in power conversion efficiency (PCE). Various materials, including ZnO, CeO₂, AZO, CuSCN, Spiro, CuI, and V₂O₅, were investigated as electron and hole transport layers in the bottom cell to optimize carrier transport. This step increased the PCE from 4.77% to 7.20% in the bottom cell. The combination of the TiO₂ reflector and the optimized bottom cell resulted in substantial improvements in the open circuit voltage (V_oc), from 0.98V to 1.71V, and PCE, from 14.26% to 20.06%.</p>