p-Phenylenediaminium iodide capping agent enabled self-healing perovskite solar cell

In this study, p-Phenylenediaminium iodide (PDAI) is used to in-situ grow a 2D (PDA)₂PbI₄ perovskite layer between (FAPbI₃)₀.₈₅(MAPbBr₃)₀.₁₅ 3D perovskite and CuSCN as a cheap hole transport layer. The results indicate that incorporating 5 mg mL⁻¹ PDAI leads to enlarged grain sizes, compact grain boundaries, reduced trap density, efficient charge extraction, and enhanced stability of the perovskite film. Passivation of the perovskite film with an appropriate amount of PDAI yields efficient perovskite solar cells with a PCE as high as 16.10%, Jsc of 21.45 mA cm⁻², Voc of 1.09 V, and FF of 70.21%, with negligible hysteresis and excellent moisture stability, retaining 99.01% of its initial PCE after 5 h at 90 ± 5% RH and showing unchanged PCE after 1440 h at 15 ± 5% RH. Most strikingly, this ultra-thin 2D passivation layer using PDA cations as a bulky spacer not only passivates surface defects but also induces self-healing properties in PSCs, enabling rapid recovery after removal from water vapor exposure. This study introduces cheap and extra-stable perovskite solar cells with outstanding self-healing ability toward commercialization.