Humidity-Induced Grain Boundaries in MAPbI3 Perovskite Films

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• 作者：Dan Li ; Simon A. Bretschneider ; Victor W. Bergmann ; Ilka M. Hermes ; Julian Mars ; Alexander Klasen ; Hao Lu ; Wolfgang Tremel ; Markus Mezger ; Hans-Jürgen Butt ; Stefan A. L. Weber ; Rüdiger Berger
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：March 31, 2016
• 年：2016
• 卷：120
• 期：12
• 页码：6363-6368
• 全文大小：410K
• ISSN：1932-7455

文摘

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.