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Aboma Mendasa, MSc, PhD. Photo.

Aboma Merdasa

Researcher

Aboma Mendasa, MSc, PhD. Photo.

Role of solution concentration in formation kinetics of bromide perovskite thin films during spin-coating monitored by optical in situ metrology

Author

  • C. Rehermann
  • V. Schröder
  • M. Flatken
  • F. Ünlü
  • O. Shargaieva
  • A. Hoell
  • A. Merdasa
  • F. Mathies
  • S. Mathur
  • E. L. Unger

Summary, in English

Optoelectronic devices based on metal halide perovskites continue to show a improved performance, and solution-based coating techniques pave the way for large-area applications. However, not all parameters influencing the thin film formation process of metal halide perovskites are identified and entirely rationalised over their full compositional range, thus hampering optimised thin film fabrication. Furthermore, while the perovskite deposition via spin-coating and annealing is an easily accessible technique, more profound insights into the chemical formation process are still lacking. Varying the precursor solution concentration is commonly used to vary the resulting thin film thickness. This study shows that varying the precursor solution concentration also affects the thin film morphology and optoelectronic quality. Hence, we herein investigate the influence of the precursor solution concentration on the formation process of a pure bromide-based triple cation perovskite (Cs0.05MA0.10FA0.85PbBr3) by fiber-based optical in situ measurement. During the spin-coating process, in situ UV-vis and PL measurements reveal formation kinetics are strongly dependent on the concentration. Furthermore, we identify delayed nucleation and retarded growth kinetics for more concentrated precursor solutions. In addition, we quantify the shifting chemical equilibrium of colloidal pre-coordination in the precursor solution depending on concentration. Namely, colloids are pre-organised to a higher degree and higher-coordination lead-bromide complexes tend to form in more concentrated precursor solutions. Thus, the modified solution chemistry rationalises retarded perovskite formation kinetics and highlights the precursor concentration as an influential and optimisable parameter for solution-based thin film deposition.

Department/s

  • LTH Profile Area: Photon Science and Technology
  • Ophthalmology Imaging Research Group
  • LTH Profile Area: Nanoscience and Semiconductor Technology
  • Chemical Physics
  • NanoLund: Centre for Nanoscience

Publishing year

2022-11-15

Language

English

Pages

32765-32774

Publication/Series

RSC Advances

Volume

12

Issue

50

Document type

Journal article

Publisher

Royal Society of Chemistry

Topic

  • Inorganic Chemistry

Status

Published

Research group

  • Ophthalmology Imaging Research Group

ISBN/ISSN/Other

  • ISSN: 2046-2069