Ultrafast Science, Volume. 3, Issue 1, 0032(2023)

High-Sensitivity Visualization of Ultrafast Carrier Diffusion by Wide-Field Holographic Microscopy

Martin Hörmann1、†, Federico Visentin1、†, Andrea Zanetta2, Johann Osmond3, Giulia Grancini2, Niek F. Hulst3,4, Matz Liebel3, Giulio Cerullo1,5, and Franco V. A. Camargo5、*
Author Affiliations
  • 1Dipartimento di Fisica, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy.
  • 2Department of Chemistry and INSTM, University of Pavia, Via T. Taramelli 14, 27100 Pavia, Italy.
  • 3ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels, Barcelona, Spain.
  • 4ICREA - Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, 08010 Barcelona, Spain.
  • 5IFN-CNR, Piazza L. da Vinci 32, 20133 Milano, Italy.
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    Ultrafast transient microscopy is a key tool to study the photophysical properties of materials in space and time, but current implementations are limited to ≈1-μm fields of view, offering no statistical information for heterogeneous samples. Recently, we demonstrated wide-field transient imaging based on multiplexed off-axis holography. Here, we perform ultrafast microscopy in parallel around a hundred diffraction-limited excitation spots over a ≈60-μm field of view, which not only automatically samples the photophysical heterogeneity of the sample over a large area but can also be used to obtain a 10-fold increase in signal-to-noise ratio by computing an average spot. We apply our microscope to study the carrier diffusion processes in methylammonium lead bromide perovskites. We observe strong diffusion due to the presence of hot carriers during the first picosecond and slower diffusion afterward. We also describe how many-body kinetics can be misleadingly interpreted as strong diffusion at high excitation densities, while at weak excitation, real diffusion is observed. Therefore, the vast increase in sensitivity offered by this technique benefits the study of carrier transport not only by reducing data acquisition times but also by enabling the measurement of the much smaller signals generated at low carrier densities.

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    Martin Hörmann, Federico Visentin, Andrea Zanetta, Johann Osmond, Giulia Grancini, Niek F. Hulst, Matz Liebel, Giulio Cerullo, Franco V. A. Camargo. High-Sensitivity Visualization of Ultrafast Carrier Diffusion by Wide-Field Holographic Microscopy[J]. Ultrafast Science, 2023, 3(1): 0032

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    Paper Information

    Category: Research Articles

    Received: Jan. 2, 2023

    Accepted: May. 30, 2023

    Published Online: Dec. 4, 2023

    The Author Email: Camargo Franco V. A. (franco.camargo@cnr.it)

    DOI:10.34133/ultrafastscience.0032

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