Perfection of Perovskite Grain Boundary Passivation by Eu‐Porphyrin Complex for Overall‐Stable Perovskite Solar Cells

The formation of defects at surfaces and grain boundaries (GBs) during the fabrication of solution‐processed perovskite film are thought to be responsible for its instability. Herein, Eu‐porphyrin complex (Eu‐pyP) is directly doped into methylammonium lead triiodide (MAPbI(3)) precursor, perfectly fabricating 2D (Eu‐pyP)(0.5)MA(n) (‐1)Pb(n)I(3) (n) (+1) platelets inlaying the GBs of 3D polycrystalline interstices in this protocol. The device based on Eu‐pyP doped perovskite film possesses a champion efficiency of 18.2%. More importantly, the doped perovskite solar cells device shows beyond 85% retention of its pristine efficiency value, whereas the pure MAPbI(3) device has a rapid drop in efficiency down to 10% within 100 h under 45% humidity at 85 °C in AM 1.5 G. The above acquired perovskite films reveal an unpredictable thermodynamic self‐healing ability. Consequently, the findings provide an avenue for defect passivation to synchronously improve resistibility to moisture, heat, and solar light including UV.