Antisolvent‐Assisted Low‐Temperature Processing of CsPbI₃ Nanocrystalline Films for Efficient Perovskite Solar Cells

CsPbI 3 perovskite nanocrystals demonstrate superior phase stability compared to their polycrystalline counterparts. High‐quality CsPbI 3 nanocrystal films are fabricated via antisolvent‐assisted deposition of NC inks and employed as photoactive layers in perovskite solar cells. However, nanocrystalline films are prone to nonuniformity or agglomeration during formation. This study investigates the effects of ethyl acetate (EA) and methyl acetate (MA) as antisolvents on the morphology of CsPbI 3 NC films and their photovoltaic properties. Results reveal that MA, with its higher volatility and faster evaporation rate, accelerates film formation while preventing nanocrystal agglomeration, thereby yielding smoother and more compact surfaces. Furthermore, a tert‐butyl iodide (TBI)‐MA solution is used to passivate surface defects of CsPbI 3 NCs, leading to improved carrier lifetime, extraction efficiency, and photovoltaic performance. By optimizing the perovskite optoelectronic properties, the best‐performing EA, MA, and TBI‐MA devices achieve progressively enhanced power conversion efficiencies of 9.30%, 11.47%, and 12.50%, respectively. Notably, compared to EA devices, MA and TBI‐MA devices exhibit significant improvements: V OC increases from 1.172 to 1.185 V and further to 1.206 V, J SC rose from 11.42 to 13.28 mA cm −2 and 14.12 mA cm −2 , and FF improved from 69.5% to 72.9% and 73.4%. Additionally, TBI‐MA devices show markedly enhanced stability under ambient conditions.