Excitonic Effects in Methylammonium Lead Halide Perovskites

Matthew Beard, Xihan Chen, Haipeng Lu, Ye Yang

Research output: Contribution to journalArticlepeer-review

112 Scopus Citations

Abstract

The exciton binding energy in methylammonium lead iodide (MAPbI3) is about 10 meV, around 1/3 of the available thermal energy (kBT ∼ 26 meV) at room temperature. Thus, exciton populations are not stable at room temperature at moderate photoexcited carrier densities. However, excitonic resonances dominate the absorption onset. Furthermore, these resonances determine the transient absorbance and transient reflectance spectra. The exciton binding energy is a reflection of the Coulomb interaction energy between photoexcited electrons and holes. As such, it serves as a marker for the strength of electron/hole interactions and impacts a variety of phenomena, such as, absorption, radiative recombination, and Auger recombination. In this Perspective, we discuss the role of excitons and excitonic resonances in the optical properties of lead-halide perovskite semiconductors. Finally, we discuss how the strong light-matter interactions induce an optical stark effect splitting the doubly spin degenerate ground exciton states and are easily observed at room temperature.

Original languageAmerican English
Pages (from-to)2595-2603
Number of pages9
JournalJournal of Physical Chemistry Letters
Volume9
Issue number10
DOIs
StatePublished - 2018

Bibliographical note

Publisher Copyright:
© 2018 American Chemical Society.

NREL Publication Number

  • NREL/JA-5900-71519

Keywords

  • excitonic resonances
  • excitons
  • optical properties
  • perovskite semiconductors
  • solar-photochemistry

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