@article{d7dede35eff7427b91e6304e160d7793,
title = "High-Resolution In-Situ Synchrotron X-Ray Studies of Inorganic Perovskite CsPbBr3: New Symmetry Assignments and Structural Phase Transitions",
abstract = "Perovskite photovoltaic ABX3 systems are being studied due to their high energy-conversion efficiencies with current emphasis placed on pure inorganic systems. In this work, synchrotron single-crystal diffraction measurements combined with second harmonic generation measurements reveal the absence of inversion symmetry below room temperature in CsPbBr3. Local structural analysis by pair distribution function and X-ray absorption fine structure methods are performed to ascertain the local ordering, atomic pair correlations, and phase evolution in a broad range of temperatures. The currently accepted space group assignments for CsPbBr3 are found to be incorrect in a manner that profoundly impacts physical properties. New assignments are obtained for the bulk structure: (Formula presented.) (above ≈410 K), P21/m (between ≈300 K and ≈410 K), and the polar group Pm (below ≈300 K), respectively. The newly observed structural distortions exist in the bulk structure consistent with the expectation of previous photoluminescence and Raman measurements. High-pressure measurements reveal multiple low-pressure phases, one of which exists as a metastable phase at ambient pressure. This work should help guide research in the perovskite photovoltaic community to better control the structure under operational conditions and further improve transport and optical properties.",
keywords = "CsPbBr, all-inorganic perovskites, in-situ single-crystal diffraction, local structure, phase transitions, space groups",
author = "Sizhan Liu and DeFilippo, {Alexander R.} and Mahalingam Balasubramanian and Zhenxian Liu and Wang, {Su Yin Grass} and Chen, {Yu Sheng} and Stella Chariton and Vitali Prakapenka and Xiangpeng Luo and Liuyan Zhao and Martin, {Jovan San} and Yixiong Lin and Yong Yan and Ghose, {Sanjit K.} and Tyson, {Trevor A.}",
note = "Funding Information: This work was supported by NSF Award DMR-1809931. This research used beamlines 7-BM, 22-IR-1, and 28-ID-2 of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. Single-crystal X-ray diffraction measurements were performed at NSF's ChemMatCARS Sector 15 at the Advanced Photon Source, which is principally supported by the National Science Foundation/Department of Energy under Grant NSF/CHE-1834750. The use of the 22-IR-1 beamline was supported by COMPRES under NSF Cooperative Agreement EAR 1606856 and CDAC (DE-NA0003975). Low-temperature XAFS measurements were conducted at Advanced Photon Source beamline 20-BM. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. L. Z. acknowledges support by NSF CAREER Grant No. DMR-174774 and AFOSR YIP Grant No. FA9550-21-1-0065. Y.Y. acknowledges support from NSF award 1851747 for perovskite materials synthesis. The authors thank C. L. Dias of the NJIT Physics Department for constructive criticism and physical insight, which has significantly improved the manuscript. They are indebted to Drs. Steven Ehrlich and Lu Ma for assistance with the XAS experiments at the NSLS2 7-BM beamline at Brookhaven National Laboratory. The authors are particularly grateful to Photon Sciences staff member James Biancarosa for repairing our cryostat, which broke apart internally during the first day of the experiment on this beamline and to staff member Steven LaMarra for fixing the electrical feedthrough after the failure. Funding Information: This work was supported by NSF Award DMR‐1809931. This research used beamlines 7‐BM, 22‐IR‐1, and 28‐ID‐2 of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE‐SC0012704. Single‐crystal X‐ray diffraction measurements were performed at NSF's ChemMatCARS Sector 15 at the Advanced Photon Source, which is principally supported by the National Science Foundation/Department of Energy under Grant NSF/CHE‐1834750. The use of the 22‐IR‐1 beamline was supported by COMPRES under NSF Cooperative Agreement EAR 1606856 and CDAC (DE‐NA0003975). Low‐temperature XAFS measurements were conducted at Advanced Photon Source beamline 20‐BM. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE‐AC02‐06CH11357. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE‐AC02‐05CH11231. L. Z. acknowledges support by NSF CAREER Grant No. DMR‐174774 and AFOSR YIP Grant No. FA9550‐21‐1‐0065. Y.Y. acknowledges support from NSF award 1851747 for perovskite materials synthesis. The authors thank C. L. Dias of the NJIT Physics Department for constructive criticism and physical insight, which has significantly improved the manuscript. They are indebted to Drs. Steven Ehrlich and Lu Ma for assistance with the XAS experiments at the NSLS2 7‐BM beamline at Brookhaven National Laboratory. The authors are particularly grateful to Photon Sciences staff member James Biancarosa for repairing our cryostat, which broke apart internally during the first day of the experiment on this beamline and to staff member Steven LaMarra for fixing the electrical feedthrough after the failure. Publisher Copyright: {\textcopyright} 2021 The Authors. Advanced Science published by Wiley-VCH GmbH",
year = "2021",
month = sep,
day = "22",
doi = "10.1002/advs.202003046",
language = "English (US)",
volume = "8",
journal = "Advanced Science",
issn = "2198-3844",
publisher = "Wiley-VCH Verlag",
number = "18",
}