Oxygen-Mediated (0D) Cs4PbX6 Formation during Open-Air Thermal Processing Improves Inorganic Perovskite Solar Cell Performance

作者：Rafikul Ali Saha, Wei‐Hsun Chiu, Giedrius Degutis, Peng Chen, Matthias Filez, Eduardo Solano, Н. К. Орлов, Francesco De Angelis, Rocío Ariza, Carlo Meneghini, Christophe Detavernier, Sawanta S. Mali, Minh Tam Hoang, Yang Yang, Erik C. Garnett, Lianzhou Wang, Hongxia Wang, Maarten B. J. Roeffaers, Julian A. Steele · 发表于：ACS Nano · 年份：2024 · DOI：10.1021/acsnano.4c03222 · 被引用次数：15 · 研究领域：Perovskite Materials and Applications、Chalcogenide Semiconductor Thin Films、Conducting polymers and applications

The desire to commercialize perovskite solar cells continues to mount, motivating the development of scalable production. Evaluations of the impact of open-air processing have revealed a variety of physical changes in the fabricated devices─with few changes having the capacity to be functionalized. Here, we highlight the beneficial role of ambient oxygen during the open-air thermal processing of metastable γ-CsPbI 3 -based perovskite thin films and devices. Physiochemical-sensitive probes elucidate oxygen intercalation and the formation of Pb–O bonds in the CsPbI 3 crystal, entering via iodine vacancies at the surface, creating superoxide (O 2 – ) through electron transfer reactions with molecular oxygen, which drives the formation of a zero-dimensional Cs 4 PbI 6 capping layer during annealing (>330 °C). The chemical conversion permanently alters the film structure, helping to shield the subsurface perovskite from moisture and introduces lattice anchoring sites, stabilizing otherwise unstable γ-CsPbI 3 films. This functional modification is demonstrated in γ-CsPbI 2 Br perovskite solar cells, boosting the operational stability and photoconversion efficiency of champion devices from 12.7 to 15.4% when annealed in dry air. Such findings prompt a reconsideration of glovebox-based perovskite solar cell research and establish a scenario where device fabrication can in fact greatly benefit from ambient oxygen.