Phase Segregation Mechanisms in Mixed-Halide CsPb(BrxI1-x)3 Nanocrystals in Dependence of Their Sizes and Their Initial [Br]:[I] Ratios

Hannah Funk, Tal Binyamin, Lioz Etgar, Oleksandra Shargaieva, Thomas Unold, Alberto Eljarrat, Christoph T. Koch, Daniel Abou-Ras*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Phase segregation in inorganic CsPb(BrxI1-x)3 nanoparticles (NPs) exhibiting originally a homogeneous [Br]:[I] mixture was investigated by means of in situ transmission electron microscopy (TEM) and evaluated by using multivariate analyses. The colloidal synthesis of the NPs offers good control of the halide ratios on the nanoscale. The spatially resolved TEM investigations were correlated with integral photoluminescence measurements. By this approach, the halide-segregation processes and their spatial distributions can be described as being governed by the interaction of three partial processes: electron- and photon-irradiation-induced iodide oxidation, local differences in band gap energy, and intrinsic lattice strain. Since the oxidation can be induced by both electron-beam and light irradiation, both irradiation types can induce phase segregation in CsPb(BrxI1-x)3 compounds. This makes in situ TEM a valuable tool to monitor phase transformation in corresponding NPs and thin films on the sub-nm scale.

Original languageAmerican English
JournalACS Materials Au
StateAccepted/In press - 2023

Bibliographical note

Funding Information:
The authors are grateful for the financial support of the Helmholtz International Research School HISCORE (HIRS-0008) and of the HyPerCells Research School. L.E. and T.B. thank the Israel Science Foundation grant no. 937/18 for the financial support. O.S. acknowledges funding from the German Science Foundation (DFG) provided in the framework of the priority program SPP 2196, “Perovskite semiconductors: From fundamental properties to devices” Project number 424394788. C.T.K. and A.E. acknowledge financial support by the German Research Foundation (DFG, project number 182087777 - SFB951).

Publisher Copyright:
© 2023 The Authors. Published by American Chemical Society.


  • in situ monitoring
  • mixed-halide perovskite nanocrystals
  • multivariate analysis
  • phase segregation
  • transmission electron microscopy


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