Photo-induced halide redistribution in organic-inorganic perovskite films

Nat Commun. 2016 May 24;7:11683. doi: 10.1038/ncomms11683.

Abstract

Organic-inorganic perovskites such as CH3NH3PbI3 are promising materials for a variety of optoelectronic applications, with certified power conversion efficiencies in solar cells already exceeding 21%. Nevertheless, state-of-the-art films still contain performance-limiting non-radiative recombination sites and exhibit a range of complex dynamic phenomena under illumination that remain poorly understood. Here we use a unique combination of confocal photoluminescence (PL) microscopy and chemical imaging to correlate the local changes in photophysics with composition in CH3NH3PbI3 films under illumination. We demonstrate that the photo-induced 'brightening' of the perovskite PL can be attributed to an order-of-magnitude reduction in trap state density. By imaging the same regions with time-of-flight secondary-ion-mass spectrometry, we correlate this photobrightening with a net migration of iodine. Our work provides visual evidence for photo-induced halide migration in triiodide perovskites and reveals the complex interplay between charge carrier populations, electronic traps and mobile halides that collectively impact optoelectronic performance.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Calcium Compounds / chemistry
  • Calcium Compounds / radiation effects*
  • Iodides / chemistry
  • Iodides / radiation effects*
  • Iodine / chemistry
  • Iodine / radiation effects
  • Lead / chemistry
  • Lead / radiation effects
  • Light
  • Luminescent Measurements / methods
  • Methylamines / chemistry
  • Methylamines / radiation effects
  • Microscopy, Confocal / methods
  • Oxides / chemistry
  • Oxides / radiation effects*
  • Spectrometry, Mass, Secondary Ion / methods
  • Titanium / chemistry
  • Titanium / radiation effects*

Substances

  • Calcium Compounds
  • Iodides
  • Methylamines
  • Oxides
  • perovskite
  • Lead
  • Iodine
  • methylamine
  • Titanium