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RESEARCH PRODUCT

Humidity-Induced Grain Boundaries in MAPbI3 Perovskite Films

Julian MarsStefan A. L. WeberAlexander KlasenMarkus MezgerWolfgang TremelIlka M. HermesDan LiHao LuRüdiger BergerSimon A. BretschneiderHans-jürgen ButtVictor W. Bergmann

subject

Materials scienceAnalytical chemistryHumidity02 engineering and technologyCrystal structureMethylammonium lead halide010402 general chemistry021001 nanoscience & nanotechnology01 natural sciences0104 chemical sciencesSurfaces Coatings and FilmsElectronic Optical and Magnetic MaterialsAtmospherechemistry.chemical_compoundCrystallographyHysteresisGeneral EnergychemistryGrain boundaryRelative humidityPhysical and Theoretical Chemistry0210 nano-technologyPerovskite (structure)

description

Methylammonium lead halide perovskites (MAPbI3) are very sensitive to humid environments. We performed in situ scanning force microscopy and in situ X-ray diffraction measurements on MAPbI3 films to track changes in the film morphology and crystal structure upon repeated exposure to a high relative humidity environment (80%). We found that the appearance of monohydrate (MAPbI3·H2O) Bragg reflections coincided with the appearance of additional grain boundaries. Prolonging the exposure time to humidity induced more grain boundaries and steps in the MAPbI3 films, and the peak intensities of the monohydrate MAPbI3·H2O increased. The monohydrate was not stable under dry atmosphere and could be reversed to MAPbI3. However, the humidity-induced grain boundaries persisted. The presence of these additional grain boundaries was most likely the reason for an increase in hysteresis in JV behavior upon humidity exposure. Morphological changes were not observed for exposure to humidity ≤50% for a duration of 144 h.

https://doi.org/10.1021/acs.jpcc.6b00335