Boosting Efficiency to 22.73%: Unraveling the Role of Solvent Environment in Low‐Dimensional Perovskites Through Competitive Bonding Interactions

Abstract It is reported that the solvent environment exerts a significant influence on the property of perovskite precursor solution and resultant film, which is more pronounced in more complex low‐dimensional perovskites. Four solvent additives with varying basicity are introduced to instigate a tug‐of‐war among bonding interactions, thereby exploring the systematic effect of the solvent environment on the growth of quantum wells and the photoelectric properties of the resultant low‐dimensional perovskite films. A governing principle that diverges significantly from those previously documented for three‐dimensional perovskites is elucidated in low‐dimensional perovskites. When coordination interactions predominate in the solvent environment, the emergence of a two‐dimensional GA₂PbI₄ transitional phase is fostered to facilitate subsequent transformation into the desirable ACI phase, and the perovskite crystallization kinetics is retarded to improve the film quality. Hence, the highest power conversion efficiency (PCE) of 22.73% is obtained for GA(MA)_nPb_nI_3n+1 (n = 5) based solar cells with a p‐i‐n structure. The PCE achieved in this work is a record among the reported low‐dimensional perovskite solar cells.