Reconstruction of the Surface for Efficient 3D/Quasi‐2D Heterostructured Inverted Perovskite Solar Cells

Abstract Energy level misalignment‐induced interfacial non‐radiative recombination and interface defect‐induced carrier transport loss are key factors limiting the power conversion efficiency (PCE) of perovskite solar cells. To address these issues, this work introduces 3‐Piperidinecarboxamide (PDN) to reconstruct the surface of the 3D perovskite. PDN passivates both shallow and deep defects simultaneously, forming an n‐type quasi‐2D perovskite surface layer that enhances electron extraction and reduces the energy level barrier. Density functional theory (DFT) calculations reveal that the electron donor unit (R‐C‐NH) of PDN preferentially binds to undercoordinated Pb 2+ defects sites on the perovskite (PVK) surface. The hydrogen bonding formed between the R‐NH 2 group of PDN and I − ions on the [PbI 6 ] 4− octahedra enhances the above binding capability. The device adopting this strategy achieves a champion PCE of 26.10%. Furthermore, unencapsulated PSCs also exhibits excellent stability, retaining 88% of the initial PCE retained after ≈1400 h at 25 °C under 30% humidity.