Signatures of Coherent Phonon Transport in Ultralow Thermal Conductivity Two-Dimensional Ruddlesden-Popper Phase Perovskites

Alexander D. Christodoulides*, Peijun Guo, Lingyun Dai, Justin M. Hoffman, Xiaotong Li, Xiaobing Zuo, Daniel Rosenmann, Alexandra Brumberg, Mercouri G. Kanatzidis, Richard D. Schaller, Jonathan A. Malen

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


An emerging class of methylammonium lead iodide (MAPbI3)-based Ruddlesden-Popper (RP) phase perovskites, BA2MAn-1PbnI3n+1 (n = 1-7), exhibit enhanced stability to environmental conditions relative to MAPbI3, yet still degrade at elevated temperatures. We experimentally determine the thermal conductivities of these layered RP phases for n = 1-6, where n defines the number of repeated perovskite octahedra per layer. We measure thermal conductivities of 0.37 ± 0.13/0.12, 0.17 ± 0.08/0.07, 0.21 ± 0.05/0.04, and 0.19 ± 0.04/0.03 W/m·K in thin films of n = 1-4 and 0.08 ± 0.06/0.04, 0.06 ± 0.04/0.03, 0.06 ± 0.03/0.03, and 0.08 ± 0.07/0.04 W/m·K in single crystals of n = 3-6. With the exception of n = 1, these thermal conductivities are lower than the range of 0.34-0.50 W/m·K reported for single-crystal MAPbI3. Reduced-order lattice dynamics modeling suggests that the initially decreasing trend of thermal conductivity in similarly oriented perovskites with increasing n may result from the transport properties of coherent phonons, emergent from the superstructure, that do not scatter at the interfaces of organic butylammonium chains and perovskite octahedra. Reduced group velocity of coherent phonons in n = 3-6, a consequence of band flattening in the phonon dispersion, is primarily responsible for their ultralow thermal conductivities. Similar effects on thermal conductivity have been experimentally demonstrated in deposited superlattices, but never in naturally defined materials such as RP phases. GIWAXS measurements reveal that higher n RP phase thin films are less orientationally controlled and therefore possess apparently elevated thermal conductivities relative to single crystals of the same n.

Original languageEnglish (US)
Pages (from-to)4165-4172
Number of pages8
JournalACS nano
Issue number3
StatePublished - Mar 23 2021


  • 2D perovskites
  • layered materials
  • methylammonium lead iodide
  • optoelectronics
  • photovoltaics
  • thermal transport

ASJC Scopus subject areas

  • Materials Science(all)
  • Engineering(all)
  • Physics and Astronomy(all)


Dive into the research topics of 'Signatures of Coherent Phonon Transport in Ultralow Thermal Conductivity Two-Dimensional Ruddlesden-Popper Phase Perovskites'. Together they form a unique fingerprint.

Cite this