Interface Molecular Orientation Engineering Induced Field Reversal for Efficient Inverted Perovskite Solar Cells

Abstract

Inverted perovskite solar cells (PSCs) continue to suffer from severe non-radiative recombination and low carrier transportation at the perovskite/C60 interface. Traditional passivation layers typically improve the device's open-circuit voltage while compromising its short-circuit current density and fill factor. To simultaneously address these issues, a multifunctional organic ammonium salt, namely 2-(4-(aminomethyl)phenyl)ethyl-1-ammonium iodide (PMEAI), was strategically engineered between perovskite and C60 interface. The horizontally aligned PMEAI suppressed both Pb- and I-vacancy defects and induced a reversal of the built-in electric field at the perovskite/C60 interface, effectively minimizing interfacial recombination losses. More importantly, it exhibited minimal molecular steric hindrance, accelerating the carrier transportation. The resultant PSCs achieve a power conversion efficiency (PCE) of 26.7% (certified PCE: 25.84%). It also obtained a remarkable PCE of 24.5% in 1 cm2 active area. The broad applicability of PMEAI as passivation layer in enabling high-performance wide-bandgap PSCs of 23.0% efficiency. Furthermore, the redirected electric field, oriented from C60 toward the perovskite, suppresses Ag+ ion migration from the electrode into the perovskite layer, thereby significantly enhancing operational stability. The PMEAI-treated devices retain 97% of their initial efficiency after 1500 h under ISOS-L-2 protocols and exhibit negligible degradation following 1344 h of ISOS-D-1 aging.