ProjectEnhancing structural coherence and optical coupling in quantum dot supercrystals
Basic data
Title:
Enhancing structural coherence and optical coupling in quantum dot supercrystals
Duration:
01/12/2024 to 30/11/2027
Abstract / short description:
Advances in the synthesis of uniformly sized nanocrystals have enabled the growth of macroscopic supercrystals through the self-assembly of nanocrystals into highly ordered, three-dimensional lattices. Compared to classical atomic crystals, nanocrystals take the role of atoms in supercrystals, which has led to the hypothesis that nanocrystals behave “quasi-atomically” in such ordered ensembles. The project tests this hypothesis with regard to a possible correlation between the structural and optical properties in supercrystals. It is based on the well-known fact that the optical properties of atomic crystals are significantly affected by nanoscale structural defects, e.g. near their surface. The project will work out whether a similar correlation also exists in supercrystals, i.e. whether the optical properties of the ordered ensemble of nanocrystals are different from those of the individual components.
This is implemented through the combination of diffraction-limited optical confocal microscopy with synchrotron-based X-ray scattering methods. Of central importance are nanodiffraction experiments, in which the X-ray beam is focused to 200 nm and less so that nanoscale defects in supercrystals can be detected with the same spatial resolution as the fluorescence, fluorescence lifetime and Raman properties in the confocal microscope. This way, correlations between the local optical properties and structural defects in the supercrystals will be revealed.
In the second part of the project, the formation of supercrystals is studied in real time using X-ray scattering methods to elucidate the basic kinetics of the formation of defects. By varying the crystallization parameters (concentration, solvent, surface ligands, etc.), in-situ X-ray scattering is applied to identify conditions under which the formation of defects can be inhibited to afford supercrystals with fewer defects.
In the third phase of the project, the previously optimized crystallization conditions are used to grow supercrystals with low defect concentration and determine their optical properties. If the initial hypothesis of an analogy between atoms and nanocrystals holds true, a significantly more homogeneous fluorescence behavior can be expected for such low-defect supercrystals. The results of the project are relevant for the application of supercrystals as superfluorescent emitters, e.g. in micro LEDs.
This is implemented through the combination of diffraction-limited optical confocal microscopy with synchrotron-based X-ray scattering methods. Of central importance are nanodiffraction experiments, in which the X-ray beam is focused to 200 nm and less so that nanoscale defects in supercrystals can be detected with the same spatial resolution as the fluorescence, fluorescence lifetime and Raman properties in the confocal microscope. This way, correlations between the local optical properties and structural defects in the supercrystals will be revealed.
In the second part of the project, the formation of supercrystals is studied in real time using X-ray scattering methods to elucidate the basic kinetics of the formation of defects. By varying the crystallization parameters (concentration, solvent, surface ligands, etc.), in-situ X-ray scattering is applied to identify conditions under which the formation of defects can be inhibited to afford supercrystals with fewer defects.
In the third phase of the project, the previously optimized crystallization conditions are used to grow supercrystals with low defect concentration and determine their optical properties. If the initial hypothesis of an analogy between atoms and nanocrystals holds true, a significantly more homogeneous fluorescence behavior can be expected for such low-defect supercrystals. The results of the project are relevant for the application of supercrystals as superfluorescent emitters, e.g. in micro LEDs.
Involved staff
Managers
Institute of Physical Chemistry (IPTC)
Department of Chemistry, Faculty of Science
Department of Chemistry, Faculty of Science
Contact persons
Faculty of Science
University of Tübingen
University of Tübingen
Institute of Applied Physics (IAP)
Department of Physics, Faculty of Science
Department of Physics, Faculty of Science
Local organizational units
Institute of Physical Chemistry (IPTC)
Department of Chemistry
Faculty of Science
Faculty of Science
Funders
Bonn, Nordrhein-Westfalen, Germany