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Title: Enhancing Ion Migration in Grain Boundaries of Hybrid Organic-Inorganic Perovskites by Chlorine

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. 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 CH 3NH 3PbI 3 perovskite films. Furthermore, this combination of diverse techniques provides a deeper understanding of the differences between ion migration within GBs and interior grains in OTP films. Our 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.

Authors:
 [1];  [2];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1376615
Alternate Identifier(s):
OSTI ID: 1400629
Grant/Contract Number:
AC05-00OR22725; AC05-00OR22750; AC02-05CH11231
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Advanced Functional Materials
Additional Journal Information:
Journal Volume: 27; Journal Issue: 26; Journal ID: ISSN 1616-301X
Publisher:
Wiley
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Yang, Bin, Brown, Chance C., Huang, Jingsong, Collins, Liam, Sang, Xiahan, Unocic, Raymond R., Jesse, Stephen, Kalinin, Sergei V., Belianinov, Alex, Jakowski, Jacek, Geohegan, David B., Sumpter, Bobby G., Xiao, Kai, and Ovchinnikova, Olga S.. Enhancing Ion Migration in Grain Boundaries of Hybrid Organic-Inorganic Perovskites by Chlorine. United States: N. p., 2017. Web. doi:10.1002/adfm.201700749.
Yang, Bin, Brown, Chance C., Huang, Jingsong, Collins, Liam, Sang, Xiahan, Unocic, Raymond R., Jesse, Stephen, Kalinin, Sergei V., Belianinov, Alex, Jakowski, Jacek, Geohegan, David B., Sumpter, Bobby G., Xiao, Kai, & Ovchinnikova, Olga S.. Enhancing Ion Migration in Grain Boundaries of Hybrid Organic-Inorganic Perovskites by Chlorine. United States. doi:10.1002/adfm.201700749.
Yang, Bin, Brown, Chance C., Huang, Jingsong, Collins, Liam, Sang, Xiahan, Unocic, Raymond R., Jesse, Stephen, Kalinin, Sergei V., Belianinov, Alex, Jakowski, Jacek, Geohegan, David B., Sumpter, Bobby G., Xiao, Kai, and Ovchinnikova, Olga S.. Fri . "Enhancing Ion Migration in Grain Boundaries of Hybrid Organic-Inorganic Perovskites by Chlorine". United States. doi:10.1002/adfm.201700749. https://www.osti.gov/servlets/purl/1376615.
@article{osti_1376615,
title = {Enhancing Ion Migration in Grain Boundaries of Hybrid Organic-Inorganic Perovskites by Chlorine},
author = {Yang, Bin and Brown, Chance C. and Huang, Jingsong and Collins, Liam and Sang, Xiahan and Unocic, Raymond R. and Jesse, Stephen and Kalinin, Sergei V. and Belianinov, Alex and Jakowski, Jacek and Geohegan, David B. and Sumpter, Bobby G. and Xiao, Kai and Ovchinnikova, Olga S.},
abstractNote = {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. 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. Furthermore, this combination of diverse techniques provides a deeper understanding of the differences between ion migration within GBs and interior grains in OTP films. Our 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.},
doi = {10.1002/adfm.201700749},
journal = {Advanced Functional Materials},
number = 26,
volume = 27,
place = {United States},
year = {Fri May 26 00:00:00 EDT 2017},
month = {Fri May 26 00:00:00 EDT 2017}
}

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  • Cited by 2
  • Organic-inorganic perovskite solar cells have attracted tremendous attention because of their remarkably high power conversion efficiencies. To further improve device performance, it is imperative to obtain fundamental understandings on the photo-response and long-term stability down to the microscopic level. Here, we report the quantitative nanoscale photoconductivity imaging on two methylammonium lead triiodide thin films with different efficiencies by light-stimulated microwave impedance microscopy. The microwave signals are largely uniform across grains and grain boundaries, suggesting that microstructures do not lead to strong spatial variations of the intrinsic photo-response. In contrast, the measured photoconductivity and lifetime are strongly affected by bulk propertiesmore » such as the sample crystallinity. As visualized by the spatial evolution of local photoconductivity, the degradation process begins with the disintegration of grains rather than nucleation and propagation from visible boundaries between grains. In conclusion, our findings provide insights to improve the electro-optical properties of perovskite thin films towards large-scale commercialization.« less
  • The efficiency of perovskite solar cells is approaching that of single-crystalline silicon solar cells despite the presence of large grain boundary (GB) area in the polycrystalline thin films. Here, by using a combination of nanoscopic and macroscopic level measurements, we show that the ion migration in polycrystalline perovskites is dominated through GBs. Conducting atomic force microscopy measurements reveal much stronger hysteresis both for photocurrent and dark-current at the GBs than on the grains interiors, which can be explained by faster ion migration at the GBs. The dramatically enhanced ion migration results in a redistribution of ions along the GBs aftermore » electric poling, in contrast to the intact grain area. The perovskite single-crystal devices without GBs show negligible current hysteresis and no ion-migration signal. Furthermore, the discovery of dominating ion migration through GBs in perovskites can lead to broad applications in many types of devices including photovoltaics, memristors, and ion batteries.« less