High-Work-Function 2D Perovskites as Passivation Agents in Perovskite Solar Cells

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).