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Updated: Jan 28, 2026

Low Pressure Vapor-assisted Solution Process for Tunable Band Gap Pinhole-free Methylammonium Lead Halide Perovskite Films
Published on: September 8, 2017
Degradation Mechanism and Relative Stability of Methylammonium Halide Based Perovskites Analyzed on the Basis of
Emilio J Juarez-Perez1, Luis K Ono1, Iciar Uriarte2,3
1Energy Materials and Surface Sciences Unit (EMSSU) , Okinawa Institute of Science and Technology Graduate University (OIST) , 1919-1 Tancha , Onna-son , Okinawa 904-0495 , Japan.
Abstract:
The correct identification of all gases released during hybrid perovskite degradation is of great significance to develop strategies to extend the lifespan of any device based on this semiconductor. CH3X (X = Br/I) is a released degradation gas/low boiling point liquid arising from methylammonium (MA+) based perovskites, which has been largely overlooked in the literature focusing on stability of perovskite solar cells. Herein, we present an unambiguous identification of CH3I release using microwave (rotational) spectroscopy. An experimental back-reaction test demonstrates that the well-known CH3NH2/HX degradation route may not be the ultimate degradation pathway of MAPbX3 in thermodynamic closed systems. Meanwhile, the CH3X/NH3 route cannot back-react selectively to MAX formation as occurred for the former back-reaction. Metadynamics calculations uncover the X halide effect on energy barriers for both degradation reactions showing a better stability of Br based perovskite ascribed to two aspects: (i) lower Brönsted-Lowry acidity of HBr compared to HI and (ii) higher nucleophilic character of CH3NH2 compared to NH3. The latter property makes CH3NH2 molecules stay preferentially attached on the electrophilic perovskite surface (Pb2+) during the dynamic simulation instead of being detached as observed for the NH3 molecule.
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