Guo, HaodanFang, YanyanLei, YanWu, JinpengLi, MinghuaLi, XiangrongCheng, Hong BoLin, YuanDyson, Paul J.2023-06-052023-06-052023-06-052023-05-2410.1002/smll.202302021https://infoscience.epfl.ch/handle/20.500.14299/198057WOS:000992098800001Wide-bandgap perovskite solar cells (PSCs) are attracting increasing attention because they play an irreplaceable role in tandem solar cells. Nevertheless, wide-bandgap PSCs suffer large open-circuit voltage (V-OC) loss and instability due to photoinduced halide segregation, significantly limiting their application. Herein, a bile salt (sodium glycochenodeoxycholate, GCDC, a natural product), is used to construct an ultrathin self-assembled ionic insulating layer firmly coating the perovskite film, which suppresses halide phase separation, reduces V-OC loss, and improves device stability. As a result, 1.68 eV wide-bandgap devices with an inverted structure deliver a V-OC of 1.20 V with an efficiency of 20.38%. The unencapsulated GCDC-treated devices are considerably more stable than the control devices, retaining 92% of their initial efficiency after 1392 h storage under ambient conditions and retaining 93% after heating at 65 degrees C for 1128 h in an N-2 atmosphere. This strategy of mitigating ion migration via anchoring a nonconductive layer provides a simple approach to achieving efficient and stable wide-bandgap PSCs.Chemistry, MultidisciplinaryChemistry, PhysicalNanoscience & NanotechnologyMaterials Science, MultidisciplinaryPhysics, AppliedPhysics, Condensed MatterChemistryScience & Technology - Other TopicsMaterials SciencePhysicsinverted perovskite solar cellsion migrationphase segregationwide-bandgappassivationcontactslengthstext::journal::journal article::research article