Optical Properties of Binary Nanocrystal Superlattices Produced by Assemblies of Strongly and Weakly Confined CsPbBr3 Perovskite Nanocrystals
Andreas Manoli a, Modestos Athanasiou a, Marios Sergides b, Taras Sekh c d, Etsuki Kobiyama e, Rainer F. Mahrt e, Maryna I. Bodnarchuk c d, Thilo Stöferle e, Maksym V. Kovalenko c d, Andreas Othonos b, Grigorios Itskos a
a Experimental Condensed Matter Physics Laboratory, Department of Physics, University of Cyprus, 1678 Nicosia, Cyprus
b Laboratory of Ultrafast Science, Department of Physics, University of Cyprus, Kallipoleos, 75, Nicosia, Cyprus
c Institute of Inorganic Chemistry, Department of Chemistry and Applied Biosciences, ETH Zürich, CH-8093 Zürich, Switzerland
d Laboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf, Switzerland.
e IBM Research Europe — Zurich, CH-8803 Rüschlikon, Switzerland
Proceedings of International Conference on Emerging Light Emitting Materials (EMLEM23)
Peyia, Cyprus, 2023 November 13th - 15th
Organizers: Grigorios Itskos, Maksym Kovalenko and Maryna Bodnarchuk
Oral, Andreas Manoli, presentation 029
Publication date: 18th August 2023

Long-range ordered nanocrystal superlattices (NC SLs) can combine the attractive properties of the individual nanocrystal constituents with new collective optoelectronic phenomena emerging through the periodic NC assembly. Perovskite NCs have emerged as highly attractive SLs building blocks, based on their facile fabrication as sharp, monodisperse cubes and the appearance of new collective effects such as superfluorescence [1]. 

Binary superlattices of the ABO6 type produced via self-assemblies of CsPbBr3 NCs, with sizes in the strong- (~5 nm) and weak- confinement (~18 nm) regime, are being demonstrated for the first time. The presented work discusses the optical properties of such binary SLs and the interactions between the strongly and weakly confined excitons. Transient photoluminescence and absorption measurements indicate efficient depletion of the small NC exciton population at the timescale of few to tens of picoseconds. Simultaneously a delay in the transient absorption rise time signal of the large NC exciton bleaching is observed. Such results support the presence of efficient energy funneling from the small to the large NCs within the binary superstructure. On-going experimental investigations are underway to provide further understanding on the impact of the energy transfer on the superfluorescence process as well as its competition with hot carrier transfer between the small and large NCs in the binary SLs.


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