Liu, YuhangAkin, SeckinPan, LinfengUchida, RyusukeArora, NehaMilic, Jovana V.Hinderhofer, AlexanderSchreiber, FrankUhl, Alexander R.Zakeeruddin, Shaik M.Hagfeldt, AndersDar, M. IbrahimGratzel, Michael2019-07-172019-07-172019-07-172019-06-0110.1126/sciadv.aaw2543https://infoscience.epfl.ch/handle/20.500.14299/159189WOS:000473798500066Preventing the degradation of metal perovskite solar cells (PSCs) by humid air poses a substantial challenge for their future deployment. We introduce here a two-dimensional (2D) A(2)PbI(4) perovskite layer using pentafluoro-phenylethylammonium (FEA) as a fluoroarene cation inserted between the 3D light-harvesting perovskite film and the hole-transporting material (HTM). The perfluorinated benzene moiety confers an ultrahydrophobic character to the spacer layer, protecting the perovskite light-harvesting material from ambient moisture while mitigating ionic diffusion in the device. Unsealed 3D/2D PSCs retain 90% of their efficiency during photovoltaic operation for 1000 hours in humid air under simulated sunlight. Remarkably, the 2D layer also enhances interfacial hole extraction, suppressing nonradiative carrier recombination and enabling a power conversion efficiency (PCE) > 22%, the highest reported for 3D/2D architectures. Our new approach provides water-and heat-resistant operationally stable PSCs with a record-level PCE.Multidisciplinary SciencesScience & Technology - Other Topicshalide perovskitesstabilitytext::journal::journal article::research article