Multisite-passivating molecules assisted regulation of perovskite crystallization kinetics for constructing high-efficiency and stable perovskite solar cells

Abstract

Additive engineering has been widely employed to address defects-related issues in perovskite solar cells, including Pb²⁺ vacancy defects, halide migration, and FA⁺ lattice mismatch. However, due to the diversity and complexity of defect types in perovskites, traditional monofunctional additives are typically limited to passivate specific types of defects and are unable to achieve effective passivation of multiple defects simultaneously. To overcome this limitation, this work proposes a multidentate synergistic coordination strategy using a multifunctional additive, ethyl 4-aminopyrazole-5-carboxylate (EAPC), to achieve coordinated passivation of multiple defects in perovskites. Combined theoretical calculations and experimental investigations reveal that the carbonyl group (C=O) of EAPC forms strong coordination bonds with uncoordinated Pb²⁺, while its amino group (–NH₂) couples with halide ions, and the pyrazole-ring N sites establish a hydrogen-bonding network with FA⁺ cations, thereby achieving triple-site synergistic passivation of Pb²⁺-X⁻-FA⁺ defects. This synergistic effect accelerates the nucleation kinetics of perovskite while retarding its growth rate, thereby reducing the defect density and enhancing the crystallinity of the resulting perovskite films. Based on this strategy, the inverted perovskite solar cells (PSCs) achieved a champion power conversion efficiency (PCE) of 24.40 %, maintaining over 90.2 % of their initial efficiency after 1000 h of aging in a N₂-glovebox environment and retaining 85.1 % of the original PCE under ambient conditions. This work pioneers a novel paradigm for synergistic defect passivation in perovskite optoelectronic devices.