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.