title: Degradation of Methylammonium Lead Iodide Perovskite Structures through Light and Electron Beam Driven Ion Migration.
abstract: Organometal halide perovskites show promising features for cost-effective application in photovoltaics. The material instability remains a major obstacle to broad application because of the poorly understood degradation pathways. Here, we apply simultaneous luminescence and electron microscopy on perovskites for the first time, allowing us to monitor in situ morphology evolution and optical properties upon perovskite degradation. Interestingly, morphology, photoluminescence (PL), and cathodoluminescence of perovskite samples evolve differently upon degradation driven by electron beam (e-beam) or by light. A transversal electric current generated by a scanning electron beam leads to dramatic changes in PL and tunes the energy band gaps continuously alongside film thinning. In contrast, light-induced degradation results in material decomposition to scattered particles and shows little PL spectral shifts. The differences in degradation can be ascribed to different electric currents that drive ion migration. Moreover, solution-processed perovskite cuboids show heterogeneity in stability which is likely related to crystallinity and morphology. Our results reveal the essential role of ion migration in perovskite degradation and provide potential avenues to rationally enhance the stability of perovskite materials by reducing ion migration while improving morphology and crystallinity. It is worth noting that even moderate e-beam currents (86 pA) and acceleration voltages (10 kV) readily induce significant perovskite degradation and alter their optical properties. Therefore, attention has to be paid while characterizing such materials using scanning electron microscopy or transmission electron microscopy techniques.
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Yuan
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Debroye
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Janssen
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Naiki
authors.affiliation: Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, KU Leuven , B-3001 Leuven, Belgium.
authors.forename: Christian
authors.initials: C
authors.lastname: Steuwe
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Gang
authors.initials: G
authors.lastname: Lu
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Michèle
authors.initials: M
authors.lastname: Moris
authors.affiliation: ISIS & icFRC, Université de Strasbourg & CNRS , 8 allée Gaspard Monge, 67000 Strasbourg, France.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Orgiu
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.|Research Institute for Electronic Science, Hokkaido University , N20W10, Kita-Ward, 001-0020 Sapporo, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Uji-I
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.
authors.forename: Frans
authors.initials: F
authors.lastname: De Schryver
authors.affiliation: ISIS & icFRC, Université de Strasbourg & CNRS , 8 allée Gaspard Monge, 67000 Strasbourg, France.
authors.forename: Paolo
authors.initials: P
authors.lastname: Samorì
authors.affiliation: Department of Chemistry, KU Leuven , Celestijnenlaan 200F, B-3001 Leuven, Belgium.|Nano-Science Center, University of Copenhagen , Universitetsparken 5, 2100 Copenhagen, Denmark.
authors.forename: Johan
authors.initials: J
authors.lastname: Hofkens
authors.affiliation: Department of Microbial and Molecular Systems, Centre for Surface Chemistry and Catalysis, KU Leuven , B-3001 Leuven, Belgium.
authors.forename: Maarten
authors.initials: M
authors.lastname: Roeffaers
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D004583:Electrons; D007454:Iodides / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008744:Methylamines / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D007454:Iodides; D008744:Methylamines; D010087:Oxides; C059910:perovskite; D007854:Lead; C027451:methylamine; D014025:Titanium