Spatially segregated free-carrier and exciton populations in individual lead halide perovskite grains

S. Nah, B. Spokoyny, C. Stoumpos, C. M.M. Soe, Mercouri G Kanatzidis, E. Harel

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

The nature of charge carriers in methylammonium lead iodide perovskites (MAPbI 3) at room temperature is still a matter of considerable debate. Here, we demonstrate that within single grains of MAPbI 3, strong spatial heterogeneities on the nanometre length scale are present and associated with simultaneous free-carrier and exciton populations. These heterogeneous populations, hidden in ensemble measurements, have a signature of spatially resolved relaxation dynamics for above-bandgap photoexcitation. Using spectrally resolved transient absorption microscopy, we directly observe both red- and blueshifts of the band-edge absorption across individual grains due to a dynamic Stark shift and screening of excitonic transitions by hot carriers. These observations help address a long-standing debate on the identity of the charge carriers, showing that both excitons and free carriers coexist, but are spatially segregated on the length scale of hundreds of nanometres.

Original languageEnglish
Pages (from-to)285-289
Number of pages5
JournalNature Photonics
Volume11
Issue number5
DOIs
Publication statusPublished - May 1 2017

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Charge carriers
Excitons
Perovskite
halides
Lead
excitons
Hot carriers
Photoexcitation
charge carriers
Iodides
Microscopic examination
Screening
Energy gap
perovskites
photoexcitation
iodides
screening
signatures
microscopy
shift

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics

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Spatially segregated free-carrier and exciton populations in individual lead halide perovskite grains. / Nah, S.; Spokoyny, B.; Stoumpos, C.; Soe, C. M.M.; Kanatzidis, Mercouri G; Harel, E.

In: Nature Photonics, Vol. 11, No. 5, 01.05.2017, p. 285-289.

Research output: Contribution to journalArticle

Nah, S. ; Spokoyny, B. ; Stoumpos, C. ; Soe, C. M.M. ; Kanatzidis, Mercouri G ; Harel, E. / Spatially segregated free-carrier and exciton populations in individual lead halide perovskite grains. In: Nature Photonics. 2017 ; Vol. 11, No. 5. pp. 285-289.
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