Regulating Spatial Charge Distribution of Multisite Passivating Additives Enables Stable Perovskite Solar Cells

Abstract The phase stability is one of the main factors restricting the efficiency and stability of perovskite solar cells (PSCs). It has been claimed that both amino and carbonyl within amide can interact with ionic defects in perovskite and stabilize perovskite phase. However, the effect of amide and its spatial distribution of charges on inhibiting perovskite degradation is still unclear. Herein, two coumarin derivatives with amide, 7‐Carbethoxyamino‐4‐methylcoumarin (MCC) and L‐glutamine‐γ‐(7‐amido‐4‐methylcoumarin) (MCG), are chosen to investigate the influence of the spatial distribution of positive and negative charges in multisite additives on stabilizing the perovskite phase. The carbonyl and amino of additives can interact with undercoordinated Pb ²⁺ , Formamidinium (FA ⁺ ) and halides of perovskite, which effectively inhibit the phase transformation of perovskite films, suppress nonradiative recombination and prolong the operating lifetime of PSC. This findings also reveal that the dipole moment of additive does not directly affect defects passivation and phase stability of perovskite, but the extended spatial distribution of amide charge augment its interaction with defect site. Due to the amphoteric molecular structure containing more alternating charges, the MCG‐modified PSC achieves a higher efficiency of 26.72% (certified 26.29%) compare to the MCC‐modified PSC (25.81%), and demonstrates superior humidity, thermal, and operational stability.