Hydrophobic interface layer improves the moisture tolerance and efficiency of ambient air-processed perovskite solar cells

Because perovskite films degrade quickly in humidity conditions, perovskite solar cells (PSCs) prepared in ambient air still show lower photovoltaic performance than those prepared in an inert atmosphere. Here, we offer an effective interfacial passivation method via a poly(N-vinylcarbazole) (PVK) layer to protect perovskite films and prevent their moisture degradation under ambient air conditions. The power conversion efficiency of the PVK-based champion PSC is 23.27% and is higher than that of the control PSC (20.94%). Meanwhile, the PVK-based perovskite films exhibit a large water contact angle, which is attributed to the hydrophobic nature of the uniformly deposited PVK layer. This leads to no significant effect for the PVK-based perovskite film with moisture degradation for 6 days under an RH of 50%, and the corresponding PVK-based PSC exhibits a higher efficiency of 21.64% and a smaller hysteresis index. Moreover, even after 3550 h of storage in an argon glovebox, the PVK-based PSC retains 98% of its initial efficiency. FA 0.95 Cs 0.05 PbI 3 perovskite films are fabricated in ambient air with RH of 40–60% and passivated by a poly(N-vinylcarbazole) (PVK) layer. The corresponding perovskite solar cell exhibits the small non-radiative open-circuit voltage loss (102 mV). The champion efficiency of perovskite solar cells achieves 23.27%, which sustains 98% of the initial PCE after about 3550 h in an argon-filled glovebox.