Crystal structures and rotational dynamics of a two-dimensional metal halide perovskite (OA)2PbI4

Xiao Hu, Depei Zhang, Tianran Chen, Alexander Z. Chen, Eric N. Holmgren, Qiang Zhang, Daniel M. Pajerowski, Mina Yoon, Guangyong Xu, Joshua J. Choi, Seung Hun Lee

Research output: Contribution to journalArticlepeer-review

10 Scopus citations

Abstract

The extended charge carrier lifetime in metal halide perovskites is responsible for their excellent optoelectronic properties. Recent studies indicate that the superb device performance in these materials is intimately related to the organic cation dynamics. Here, we focus on the investigation of the two-dimensional hybrid perovskite, (C8H17NH3)2PbI4 (henceforth, OA+ = C8H17NH3+). Using elastic and quasielastic neutron scattering techniques and group theoretical analysis, we studied the structural phase transitions and rotational modes of the C8H17NH3+ cation in (OA)2PbI4. Our results show that, in the high-temperature orthorhombic (T > 310 K) phase, the OA+ cation exhibits a combination of a twofold rotation of the NH3-CH2 head group about the crystal c-axis with a characteristic relaxation time of ∼6.2 ps, threefold rotations (C3) of NH3 and CH3 terminal groups, and slow librations of the other atoms. Contrastingly, only the C3 rotation is present in the intermediate-temperature orthorhombic (238 K < T < 310 K) and low-temperature monoclinic (T < 238 K) phases.

Original languageEnglish
Article number014703
JournalJournal of Chemical Physics
Volume152
Issue number1
DOIs
StatePublished - Jan 7 2020

Funding

This work at the University of Virginia was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Award No. DE-SC0016144. The research at Oak Ridge National Laboratory’s Spallation Neutron Source was sponsored by the U.S. Department of Energy, Office of Basic Energy Sciences. This research used resources at Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. The computational work was performed by utilizing the resources at the National Energy Research Scientific Computing (NERSC) Center, which is supported by the Office of Science of the U.S. Department of Energy (Contract No. DE-AC02-05CH11231). We acknowledge the support of the National Institute of Standards and Technology, U.S. Department of Commerce, in providing the neutron research facilities used in this work.

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