Efficient MA-Free Perovskite Solar Cells Enabled by a Solvent-Engineering-Assisted Low-Dimensional Passivation Strategy

Quasi-two-dimensional(Q-2D) perovskites hold significant promise for perovskite photovoltaic applications. While Q-2D surface treatment is widely employed to enhance perovskite solar cell (PSC) performance, conventional passivation strategies often exhibit uncontrolled penetration of passivation molecules into the three-dimensional (3D) perovskite lattice, leading to unintended structural disruptions. By leveraging solvent engineering to tailor the passivation environment on the 3D perovskite surface, octyl-ammonium iodide (OAI), a long-chain quaternary ammonium salt utilized in Q-2D passivation, functions with enhanced efficiency and stability, thereby optimizing the efficacy of Q-2D passivation in photovoltaic performance enhancement. This hybrid strategy effectively repurposes residual PbI₂ as a functional template to mediate the growth of a high-quality 2D/3D heterostructure. Consequently, the cooptimized FACs-based PSCs achieve a remarkable power conversion efficiency of 24.98%, validating the significant advantages of this synergistic approach. ToF-SIMS analysis further confirms that the solvent-engineered Q-2D passivation strategy suppresses destructive infiltration of OA⁺. The Q-2D perovskite layer functions as a multifunctional protective barrier, simultaneously providing a hydrophobic shield against environmental degradation while enhancing the charge transport efficiency and long-term operational stability. These findings highlight the transformative potential of Q-2D perovskites in advancing next-generation photovoltaics with industrial scalability and durability.