Abstract
Ionicity plays an important role in determining material properties, as well as optoelectronic performance of organometallic trihalide perovskites (OTPs). Ion migration in OTP films has recently been under intensive investigation by various scanning probe microscopy (SPM) techniques. However, controversial findings regarding the role of grain boundaries (GBs) associated with ion migration are often encountered, likely as a result of feedback errors and topographic effects common in to SPM. In this work, electron microscopy and spectroscopy (scanning transmission electron microscopy/electron energy loss spectroscopy) are combined with a novel, open-loop, band-excitation, (contact) Kelvin probe force microscopy (BE-KPFM and BE-cKPFM), in conjunction with ab initio molecular dynamics simulations to examine the ion behavior in the GBs of CH3NH3PbI3 perovskite films. This combination of diverse techniques provides a deeper understanding of the differences between ion migration within GBs and interior grains in OTP films. This work demonstrates that ion migration can be significantly enhanced by introducing additional mobile Cl− ions into GBs. The enhancement of ion migration may serve as the first step toward the development of high-performance electrically and optically tunable memristors and synaptic devices.
Original language | English |
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Article number | 1700749 |
Journal | Advanced Functional Materials |
Volume | 27 |
Issue number | 26 |
DOIs | |
State | Published - Jul 12 2017 |
Funding
This research was conducted at the Center for Nanophase Materials Sciences (CNMS), which is a Department of Energy (DOE) Office of Science User Facility. The MD simulations used the resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory and of the National Energy Research Scientific Computing Center, which were supported by the Office of Science of the U.S. DOE under Contract Nos. DE-AC05-00OR22750 and DE-AC02-05CH11231, respectively.
Keywords
- Kelvin probe force microscopy
- grain boundaries
- ion migration
- organometallic trihalide perovskites