Liu, ChengSun, XiuhongYang, YiSyzgantseva, Olga A.Syzgantseva, Maria A.Ding, BinShibayama, NaoyukiKanda, HiroyukiTirani, Farzaneh FadaeiScopelliti, RosarioZhang, ShunlinBrooks, Keith G.Dai, SongyuanCui, GuangleiIrwin, Michael D.Shao, ZhipengDing, YongFei, ZhaofuDyson, Paul J.Nazeeruddin, Mohammad Khaja2023-07-312023-07-312023-07-312023-05-2610.1126/sciadv.adg0087https://infoscience.epfl.ch/handle/20.500.14299/199559WOS:001009447100013All-inorganic CsPbI3 perovskite solar cells (PSCs) with efficiencies exceeding 20% are ideal candidates for appli-cation in large-scale tandem solar cells. However, there are still two major obstacles hindering their scale-up: (i) the inhomogeneous solid-state synthesis process and (ii) the inferior stability of the photoactive CsPbI3 black phase. Here, we have used a thermally stable ionic liquid, bis(triphenylphosphine)iminium bis(trifluoromethyl-sulfonyl)imide ([PPN][TFSI]), to retard the high-temperature solid-state reaction between Cs4PbI6 and DMAPbI3 [dimethylammonium (DMA)], which enables the preparation of high-quality and large-area CsPbI3 films in the air. Because of the strong Pb-O contacts, [PPN][TFSI] increases the formation energy of superficial vacancies and prevents the undesired phase degradation of CsPbI3. The resulting PSCs attained a power conversion efficiency (PCE) of 20.64% (certified 19.69%) with long-term operational stability over 1000 hours. A record efficiency of 16.89% for an all-inorganic perovskite solar module was achieved, with an active area of 28.17 cm2.Multidisciplinary SciencesScience & Technology - Other Topicshalide perovskitescrystalsalttext::journal::journal article::research article