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The Influence of Water Vapor on the Stability and Processing of Hybrid Perovskite Solar Cells Made from Non‐Stoichiometric Precursor Mixtures
Author(s) -
Petrus Michiel L.,
Hu Yinghong,
Moia Davide,
Calado Philip,
Leguy Aurélien M. A.,
Barnes Piers R. F.,
Docampo Pablo
Publication year - 2016
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201600999
Subject(s) - materials science , perovskite (structure) , stoichiometry , photocurrent , iodide , annealing (glass) , chemical engineering , grain boundary , grain size , moisture , inorganic chemistry , chemistry , optoelectronics , composite material , microstructure , engineering
We investigated the influence of moisture on methylammonium lead iodide perovskite (MAPbI 3 ) films and solar cells derived from non‐stoichiometric precursor mixtures. We followed both the structural changes under controlled air humidity through in situ X‐ray diffraction, and the electronic behavior of devices prepared from these films. A small PbI 2 excess in the films improved the stability of the perovskite compared to stoichiometric samples. We assign this to excess PbI 2 layers at the perovskite grain boundaries or to the termination of the perovskite crystals with Pb and I. In contrast, the MAI‐excess films composed of smaller perovskite crystals showed increased electronic disorder and reduced device performance owing to poor charge collection. Upon exposure to moisture followed by dehydration (so‐called solvent annealing), these films recrystallized to form larger, highly oriented crystals with fewer electronic defects and a remarkable improvement in photocurrent and photovoltaic efficiency.