Efficient and Stable Wide‐Bandgap Methylammonium‐Free Perovskite Solar Cells by Simultaneous Passivation and Cleaning with Diamine

Wide‐bandgap perovskite solar cells (WBG‐PSCs) are pivotal in achieving high‐performance tandem solar cells. However, their power conversion efficiency (PCE) is limited by the losses from the interfacial charge transfer barrier and nonradiative recombination. In this investigation, 1,4‐bis(aminomethyl)benzene (PDMA) is employed as a defect passivator for fabricating methylammonium (MA)‐free perovskite solar cells (PSCs), thus effectively mitigating nonradiative recombination losses of charge carriers. Meanwhile, PDMA molecules chemically rinse the perovskite film to create a grooved surface, leading to the increase of contact area between the perovskite and electron transport layer to further improve the interfacial charge transfer. As a result, the PSCs based on these surface‐passivated and chemically cleaned perovskite films present a champion PCE of 21.23% ( E g = 1.68 eV) compared to the control devices with a PCE of 18.23%, while maintaining over 80% efficiency after 800 h storage in ambient air. This study presents a highly effective approach for one‐step passivation and chemical cleaning of wide‐bandgap perovskite for efficient and stable solar cells, offering valuable insights for future research in this field.