Critical phonon frequency renormalization and dual phonon coexistence in layered Ruddlesden-Popper inorganic perovskites

Zezhu Zeng, Chen Chen, Cunzhi Zhang, Qian Zhang, and Yue Chen
Phys. Rev. B 105, 184303 – Published 13 May 2022
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Abstract

Phonon-related behaviors such as hot-carrier bottleneck and thermooptic coefficients stimulate the study of lattice dynamics and thermal conductivity (κ) in perovskites. Herein, we report ultralow thermal conductivities of synthesized highly oriented samples of Cs2PbI2Cl2 ( 0.45 W/mK at 300 K) and Cs2SnI2Cl2 ( 0.60 W/mK at 300 K). Phonon frequency renormalization of the octahedral rotational soft modes in Cs2PbI2Cl2 triggered by the fourth-order anharmonicity considerably amends the three- and four-phonon linewidths, significantly altering the thermal transport property of Cs2PbI2Cl2. Furthermore, the phonon gas model partially breaks down, and both normal and diffuson-like phonons must be considered to capture the nearly temperature-independent κ of Cs2PbI2Cl2. We also find these unusual phonon behaviors in other layered inorganic perovskites such as Cs2PbBr2Cl2 and Cs2SnI2Cl2. Our results rationalize the crucial high-order phonon interactions and two-channel lattice thermal transports in perovskites with ultralow κ.

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  • Received 15 September 2021
  • Revised 22 December 2021
  • Accepted 27 April 2022

DOI:https://doi.org/10.1103/PhysRevB.105.184303

©2022 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Zezhu Zeng1,*, Chen Chen1,*, Cunzhi Zhang2,*, Qian Zhang3, and Yue Chen1,4,†

  • 1Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China
  • 2Pritzker School of Molecular Engineering, The University of Chicago, Chicago, Illinois, USA
  • 3School of Materials Science and Engineering, Harbin Institute of Technology, Shenzhen 518055, China
  • 4HKU Zhejiang Institute of Research and Innovation, 1623 Dayuan Road, Lin An 311305, China

  • *These authors contributed equally to this work.
  • yuechen@hku.hk

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Issue

Vol. 105, Iss. 18 — 1 May 2022

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