title: Observation of Nanoscale Morphological and Structural Degradation in Perovskite Solar Cells by in Situ TEM.
abstract: High-resolution in situ transmission electron microscopy (TEM) and electron energy loss spectroscopy were applied to systematically investigate morphological and structural degradation behaviors in perovskite films during different environmental exposure treatments. In situ TEM experiment indicates that vacuum itself is not likely to cause degradation in perovskites. In addition, these materials were found to degrade significantly when they were heated to ∼50-60 °C (i.e., a solar cell's field operating temperature) under illumination. This observation thus conveys a critically important message that the instability of perovskite solar cells at such a low temperature may limit their real field commercial applications. It was further unveiled that oxygen most likely attacks the CH3NH3+organic moiety rather than the PbI6component of perovskites during ambient air exposure at room temperature. This finding grants a deeper understanding of the perovskite degradation mechanism and suggests a way to prevent degradation of perovskites by tailoring the organic moiety component.
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.|Department of Materials Science and Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Dyck
authors.affiliation: Materials Science & Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Wenmei
authors.initials: W
authors.lastname: Ming
authors.affiliation: Materials Science & Technology Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Mao-Hua
authors.initials: MH
authors.lastname: Du
authors.affiliation: Department of Electrical Engineering and Computer Science, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Sanjib
authors.initials: S
authors.lastname: Das
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Rouleau
authors.affiliation: Department of Materials Science and Engineering, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Gerd
authors.initials: G
authors.lastname: Duscher
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: David B
authors.initials: DB
authors.lastname: Geohegan
authors.affiliation: Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Kai
authors.initials: K
authors.lastname: Xiao
keywords: degradation; electron energy loss spectroscopy; organometallic halide perovskite; perovskite solar cell; transmission electron microscopy