Phonon Screening of Excitons in Semiconductors: Halide Perovskites and Beyond

Marina R. Filip, Jonah B. Haber, and Jeffrey B. Neaton
Phys. Rev. Lett. 127, 067401 – Published 5 August 2021
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Abstract

The ab initio Bethe-Salpeter equation (BSE) approach, an established method for the study of excitons in materials, is typically solved in a limit where only static screening from electrons is captured. Here, we generalize this framework to include dynamical screening from phonons at lowest order in the electron-phonon interaction. We apply this generalized BSE approach to a series of inorganic lead halide perovskites, CsPbX3, with X=Cl, Br, and I. We find that inclusion of screening from phonons significantly reduces the computed exciton binding energies of these systems. By deriving a simple expression for phonon screening effects, we reveal general trends for their importance in semiconductors and insulators, based on a hydrogenic exciton model. We demonstrate that the magnitude of the phonon screening correction in isotropic materials can be reliably predicted using four material specific parameters: the reduced effective mass, static and optical dielectric constants, and frequency of the most strongly coupled longitudinal-optical phonon mode. This framework helps to elucidate the importance of phonon screening and its relation to excitonic properties in a broad class of semiconductors.

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  • Received 6 March 2020
  • Revised 5 December 2020
  • Accepted 4 June 2021

DOI:https://doi.org/10.1103/PhysRevLett.127.067401

© 2021 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Marina R. Filip1,2,3,†, Jonah B. Haber2,†, and Jeffrey B. Neaton2,4,5,*

  • 1Department of Physics, University of Oxford, Oxford OX1 3PJ, United Kingdom
  • 2Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
  • 3Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 4Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
  • 5Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720, USA

  • *jbneaton@lbl.gov
  • M. R. F. and J. B. H. contributed equally to this work.

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Vol. 127, Iss. 6 — 6 August 2021

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