Various approaches have been employed to passivate the defects in perovskite films used in perovskite solar cells (PSCs). However, the passivation mechanism is often unclear at a molecular level, and the reason for enhanced PSC performance often remains elusive. Here, we explore the impact of passivation with high-work-function two-dimensional (2D) perovskites in promoting the efficiency of PSCs. We realized that 4-halophenylethylammonium lead iodide possesses a high work function, causing band bending at the perovskite surface, thus suppressing charge carrier recombination at the perovskite/hole transporting material (HTM) interface by forming a barricade for electrons to recombine at the trap states. Utilizing this strategy leads to a similar to 100 mV improvement in voltage and a similar to 2.5% increase in power conversion efficiency (PCE).