Kanda, HiroyukiShibayama, NaoyukiHuckaba, Aron JoelLee, YonghuiPaek, SanghyunKlipfel, NadjaRoldan-Carmona, CristinaQueloz, Valentin Ianis EmmanuelGrancini, GiuliaZhang, YiAbuhelaiga, MousaCho, Kyung TaekLi, MoMensi, Mounir DrissKinge, SachinNazeeruddin, Mohammad Khaja2020-05-102020-05-102020-05-102020-04-0110.1039/c9ee02028dhttps://infoscience.epfl.ch/handle/20.500.14299/168678WOS:000528728700016Surface passivation of the perovskite photo absorber is a key factor to improve the photovoltaic performance. So far robust passivation strategies have not yet been revealed. Here, we demonstrate a successful passivation strategy which controls the Fermi-level of the perovskite surface by improving the surface states. Such Fermi-level control caused band-bending between the surface and bulk of the perovskite, which enhanced the hole-extraction from the absorber bulk to the HTM side. As an added benefit, the inorganic passivation layer improved the device light stability. By depositing a thick protection layer on the complete device, a remarkable waterproofing effect was obtained. As a result, an enhancement of VOC and the conversion efficiency from 20.5% to 22.1% was achieved. We revealed these passivation mechanisms and used perhydropoly(silazane) (PHPS) derived silica to control the perovskite surface states.Chemistry, MultidisciplinaryEnergy & FuelsEngineering, ChemicalEnvironmental SciencesChemistryEngineeringEnvironmental Sciences & Ecologyphotoelectron-spectroscopyhalide perovskitesefficientelectrontrihalidelengthsoxynitrideinterfacestabilitylayertext::journal::journal article::research article