Co‐Assembled Hybrid Interlayer Engineering for Enhanced Upper Interface Stability in Inverted Perovskite Solar Cells

ABSTRACT Engineering electron transport layer (ETL) interface is critical for high‐efficiency and long‐term stability in inverted perovskite solar cells (PSCs), yet co‐assembled hybrid interlayer are rarely explored for this upper interface. This work integrates 4‐aminobenzoate acid hydrochloride (4AA) with a dibenzo‐18‐crown‐6 (DB18C6) to construct a hybrid interlayer at ETL interface. The 4AA molecules intercalate into DB18C6 aggregates, homogenizing the monolayer and boosting surface coverage (from 0.57 to 0.79) and strengthening the interfacial dipole moment (from 2 to 7 Debye). This interlayer provides dual passivation, in which the ─NH 3 + and ─COOH groups of 4AA neutralize ionic defects, while DB18C6 optimizes perovskite crystallinity and energy level alignment. Therefore, modified devices achieve an efficiency of 26.33% (exceeding 22.92% of the control) with high open‐circuit voltage (V OC ) of 1.167 V and fill factor (FF) of 86.05% (compared to 1.130 V and 80.38% of the control). More importantly, the co‐assembled hybrid interlayer serves as a barrier against environmental and ionic degradation. The unencapsulated device demonstrates outstanding operational stability, retaining 93.2% of initial efficiency after 1000 h of maximum power point tracking. This work demonstrates a co‐assembly strategy to address efficiency and stability challenges at ETL interface, paving a reliable path toward high‐performance and stable inverted PSCs.