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

In this study, p-Phenylenediaminium iodide (PDAI) is used to in-situ growth of 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 the incorporation of 5 mg mL^-1 PDAI leads to enlarged grain sizes, compact grain boundaries, reduced trap density, efficient charge extraction, and enhanced stability of perovskite film. Passivation of perovskite film with the appropriate amount of PDAI helps in achieving efficient perovskite solar cell with a PCE as high as 16.10%, a J_SC of 21.45 mA cm^-2, a V_OC of 1.09 V, and FF of 70.21%, with negligible hysteresis and excellent moisture stability which remains 99.01% of its initial PCE value after 5 h in high relative humidity of 90 ± 5% and shows unchanged PCE after 1440 h in low relative humidity of 15 ± 5%. Most strikingly, this ultra-thin 2D passivation layer by the use of PDA cations as a bulky spacer not only passivates the defects on the surface of perovskite film but also induces self-healing properties in PSCs which can be rapidly recovered after keeping away from water vapor exposure. This study introduces the cheap and extra stable perovskite solar cells with outstanding self-healing ability towards commercialization.