Temperature-driven anion migration in gradient halide perovskites



Cesium lead halide perovskite films with a systematic change in the halide composition of CsPbBr3−xIx, in which iodide concentration varies from x = 0 to x = 3, provide a built-in gradient band structure. Such a gradient structure allows for the integrated capture of visible photons and directs them to the energetically low-lying iodide rich region. Annealing gradient halide perovskite films at temperatures ranging from 50 ○C to 90 ○C causes the films to homogenize into mixed halide perovskites. The movement of halide ions during the homogenization process was elucidated using UV-Visible absorbance and X-ray photoelectron spectroscopy. The halide ion movement in CsPbBr3−xIx gradient films was tracked via absorbance changes in the visible region of the spectrum that enabled us to measure the temperature dependent rate constant and energy of activation (74.5 kJ/mol) of halide ion homogenization. Excited state processes of both gradient and homogenized films probed through transient absorption spectroscopy showed the direct flow of charge carriers and charge recombination in both films.


Attribute NameValues
  • Prashant Kamat

Journal or Work Title
  • Journal of Chemical Physics

  • 151

  • October

First Page
  • 134703

Publication Date
  • 2019-10

  • Magellan SEM

  • AIP Publishing

Date Created
  • 2019-10-08

  • English

Departments and Units
Record Visibility Public
Content License
  • All rights reserved

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