In Situ X-Ray Scattering Study on the Formation of CsPbBr3 Perovskite Nanocrystals

Federico Montanarella^a^,^d, Quinten Akkerman^a^,^d, Tim Prins^b, Dennis Bonatz^c, Maaike van der Sluijs^b, Johanna van der Bok^b, Daniel Vanmaekelbergh^b, Alf Mews^c, Maksym Kovalenko^a^,^d

^aDepartment of Chemistry and Applied Biosciences, Institute of Inorganic Chemistry, ETH Zürich, Zürich, Switzerland

^bUtrecht University, Condensed Matter and Interfaces, Debye Institute for nanomaterials science, Netherlands

^cUniversity of Hamburg, Institute of Physical Chemistry, Hamburg, Germany

^dLaboratory of Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Dübendorf, Switzerland, Ueberlandstrasse, 129, Dübendorf, Switzerland

Proceedings of Internet NanoGe Conference on Nanocrystals (iNCNC)

Online, Spain, 2021 June 28th - July 2nd

Organizers: Maksym Kovalenko, Maria Ibáñez, Peter Reiss and Quinten Akkerman

Oral, Federico Montanarella, presentation 018
DOI: https://doi.org/10.29363/nanoge.incnc.2021.018
Publication date: 8th June 2021

Lead halide perovskite (LHP) nanocrystals are the rising star in the quantum dots field.[1] Their remarkable optical properties made them a promising material for several applications such as lighting and LEDs.[2] Although chemists can produce high quality LHP nanocrystals, deep understanding of the formation mechanism underlying this material is still limited, thus hampering the research on this topic. The main drawbacks to a complete and deep investigation of this process are: the fast reaction kinetics, the extensive range of by-products, and the high temperatures required for the synthesis. These reasons substantially hamper the possibility to use conventional characterization techniques such as, for example, ex situ absorption. In this regard, there are few reports on the formation mechanism of LHP nanocrystals but either only via indirect measurements or in experimental conditions far from lab standards.

Recently synchrotron-based X-ray scattering techniques have proven to be a valid platform for the study of the formation mechanism of nanocrystals.[3] The high time resolution and the high signal-to-noise ratio, combined with the possibility to probe the average nanocrystal population, in situ, in chemical environments identical to those used in the labs, promotes this technique as an ideal candidate for the study of LHP nanocrystals.

In order to shed light on the formation mechanism of LHP nanocrystals, we performed synchrotron-based time-resolved in-situ small- and wide-angle X-ray scattering (SAXS & WAXS) measurements on forming nanocrystals in a custom-made three neck flask. The high time resolution (~ ms), combined with the high brilliance of synchrotron radiation, allowed us to follow the formation of the nanocrystals from nucleation to full growth. In particular, we were able to extract the evolution of particle size distribution and concentration throughout the synthesis. The extracted information are combined to give full description of the formation process, allowing us to propose a formation mechanism and a path toward the production of monodispersed LHP nanocrystals.

References:

[1] Akkerman, Q.A., Rainò, G., Kovalenko, M.V. et al. Genesis, challenges and opportunities for colloidal lead halide perovskite nanocrystals. Nature Mater. 17, 394–405 (2018).

[2] Kovalenko, M.V., Protesescu, L., Bodnarchuk, M.I.Properties and potential optoelectronic applications of lead halide perovskite nanocrystals. Science 358, 745–750 (2017).

[3] Prins, P.T., Montanarella, F., Dümbgen, K. et al. Extended Nucleation and Superfocusing in Colloidal Semiconductor Nanocrystal Synthesis. Nano Letters 21, 6, 2487–2496 (2021).

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