Mechanistic Origins of Excitonic Properties in 2D Perovskites: Implications for Exciton Engineering

Kameron Hansen, Cindy Wong, C. McClure, Blake Romrell, Laura Flannery, Daniel Powell, Kelsey Garden, Alex Berzansky, Michelle Eggleston, Daniel King, Carter Shirley, Matthew Beard, Wanyi Nie, Andre Schleife, John Colton, Luisa Whittaker-Brooks

Research output: Contribution to journalArticlepeer-review

6 Scopus Citations

Abstract

As the field of 2D halide perovskites (HPs) matures, state-of-the-art techniques to measure important properties, such as the band gap (Eg) and exciton binding energy (Eb), continue to produce inconsistent values. Here, we tackle this long-standing problem by obtaining direct measurements of Eg and Eb for 31 unique HP structures. The Eb values are lower than in previous literature reports and lower than expected from standard theory that assumes excitons are screened by optical-frequency dielectric constants. These low Eb values are shown to be a consequence of unique screening effects, such as superlattice screening and phonon screening. We find a strikingly strong correlation between Eb and Eg and provide design principles to a priori tune Eg and Eb to their optimal values. As such, this work offers a blueprint for Eg-Eb engineering of low-dimensional semiconductors as an even more useful replacement for simply band-gap engineering.
Original languageAmerican English
Pages (from-to)3463-3482
Number of pages20
JournalMatter
Volume6
Issue number10
DOIs
StatePublished - 2023

NREL Publication Number

  • NREL/JA-5900-87580

Keywords

  • 2D semiconductor
  • band-gap engineering
  • charge-lattice interactions
  • dielectric function
  • electroabsorption
  • halide perovskite
  • phonon screening
  • quantum well
  • superlattice
  • Wannier exciton

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