Suppressing Vacancies via Tailored Molecular Interactions Toward Enhanced Moisture Stability in Fully Air‐Fabricated Inverted Perovskite Solar Cells

Fabrication of perovskite solar cells (PSCs) under fully ambient atmospheric conditions can expedite their large‐scale production and industrialization. However, vacancy defects are readily formed during film formation, triggering perovskite hydration reactions, ultimately causing material degradation and thus limiting device efficiency. In this work, we tailored additive molecules to incorporate 2,5‐diaminoterephthalic acid (DATPA), an aromatic molecule bearing two symmetric amino and carboxyl groups, into the perovskite bulk phase, thus gradually mitigating cationic and anionic vacancies and thereby suppressing moisture penetration. The amino and carboxyl groups of the aforementioned additives can interact with the cations and halide ions in perovskites, thereby occupying the vacant A‑sites and X‑sites at grain boundaries, increasing the binding energy between perovskites and water molecules, and consequently enhancing moisture resistance. This strategy effectively ameliorates the crystallization process of perovskites under ambient air conditions at room temperature, facilitating the achievement of structural uniformity. The DATPA‐modified PSCs fabricated under fully ambient air conditions achieved champion power conversion efficiencies (PCEs) of 25.17% and 24.53% with aperture areas of 0.034 and 1 cm 2 , respectively. The unencapsulated PSCs retained 88% of their initial performance after 1500 h of aging under ambient air conditions (50% relative humidity) at room temperature.