The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Aboma Mendasa, MSc, PhD. Photo.

Aboma Merdasa

Researcher

Aboma Mendasa, MSc, PhD. Photo.

Origin of Ionic Inhomogeneity in MAPb(IxBr1-x)3Perovskite Thin Films Revealed by In-Situ Spectroscopy during Spin Coating and Annealing

Author

  • Carolin Rehermann
  • Aboma Merdasa
  • Klara Suchan
  • Vincent Schröder
  • Florian Mathies
  • Eva L. Unger

Summary, in English

Irradiation-induced phase segregation in mixed methylammonium halide perovskite samples such as methylammonium lead bromide-iodide, MAPb(IxBr1-x)3, is being studied intensively because it limits the efficiency of wide band gap perovskite solar cells. It has been postulated that this phenomenon depends on the intrinsic ionic (in)homogeneity in samples already induced during film formation. A deeper understanding of the MAPb(IxBr1-x)3 formation processes and the influence of the halide ratio, solvents, and the perovskite precursor composition as well as the influence of processing parameters during deposition, e.g., spin coating and annealing parameters, is still lacking. Here, we use a fiber optic-based optical in-situ setup to study the formation processes of the MAPb(IxBr1-x)3 series on a subsecond time scale during spin coating and thermal annealing. In-situ UV-vis measurements during spin coating reveal the influence of different halide ratios, x, in the precursor solution on the preferential crystallization of the phase. Pure bromide samples directly form a perovskite phase, samples with high iodide content form a solvate intermediate phase, and samples with a mixed stoichiometry between 0.1 ≤ x ≤ 0.6 form both. This leads to a heterogeneous formation process via two competing reaction pathways, that leads to a heterogeneous mixture of phases, during spin coating and rationalizes the compositional heterogeneity of mixed bromide-iodide samples even after annealing.

Department/s

  • Combustion Physics
  • Chemical Physics
  • NanoLund: Centre for Nanoscience

Publishing year

2020-07-08

Language

English

Pages

30343-30352

Publication/Series

ACS Applied Materials and Interfaces

Volume

12

Issue

27

Document type

Journal article

Publisher

The American Chemical Society (ACS)

Topic

  • Chemical Sciences

Keywords

  • formation process
  • homogeneity
  • in-situ spectroscopy
  • mixed halides
  • perovskites

Status

Published

ISBN/ISSN/Other

  • ISSN: 1944-8244