An Interpenetrating Alumina-2D Perovskite Structure for Synergistic Passivation in Carbon-Based Perovskite Solar Cells.

Carbon-based perovskite solar cells (C-PSCs) have attracted extensive attention due to their excellent environmental stability and low cost. 2D perovskite passivation has been widely employed as an effective strategy to enhance device stability in C-PSCs. However, this strategy often fails to simultaneously enhance efficiency and stability, owing to the random crystallization and disordered distribution of the 2D perovskite phase. Herein, phenethylammonium iodide and aluminum oxide (Al2O3) are employed to regulate the growth of 2D perovskites, forming an ordered interpenetrating alumina-2D perovskite structure. This unique architecture not only suppresses surface defects in the perovskite but also establishes an energy-level gradient, thereby improving energy-level alignment and facilitating interfacial charge extraction. Consequently, the hole transport layer-free C-PSCs fabricated under ambient air conditions achieved a power conversion efficiency of 18.1% and a T80 stability of 2500 h, demonstrating the effectiveness of the Al2O3-2D perovskite structure in enabling highly efficient and stable C-PSCs.