Homogeneously‐Dimensionalizing Perovskite Surface by Dual‐Mechano‐Chemical Regulation for Efficient Solar Cells

Precise manipulation on surface dimensionality benefits the improvement of efficiency and stability of perovskite solar cells, however, heterogeneity with the presence of substantial atomic-scale impurities and micro-wrinkles on perovskite surface that serve as transformation template challenges the formation of homogeneous heterointerface and thus weakens healing efficacy. To address this issue, herein, we propose a dual-mechano-chemical strategy is proposed to homogenize the morphologic-compositional feature of perovskite surface by first polishing superficial nano-impurities with energetic nanoparticles and then in situ dimensionalizing the defect-free lattice to form a 2D/3D heterointerface with strengthened contact and homogeneous distribution. With the implement of this strategy, the reconstructed heterointerface not only accelerates charge transfer with minimized interfacial non-radiative recombination losses, but also protects perovskite lattice from external attack. Consequently, an all-air-processed carbon-based CsPbI₂Br solar cell displays enhanced efficiency of 15.29% and elevated performance retention rate under dark storage over 1000 h, high temperature over 500 h as well as persistent operation over 200 h. This work provides a multidimensional surface engineering strategy for high-efficiency and stable perovskite-based photoelectric device, benefiting the large-scale fabrication in the future.