Three-photon cascaded emission from triexcitons in giant CsPbBr3 quantum dots

Miri Kazes^a, Dekel Nakar^a, Ihor Cherniukh^b^,^c, Mayna I. Bodnarchuk^b^,^d, Leon G. Feld^b^,^c^,^d, Chenglian Zhu^b^,^c, Daniel Amgar^a, Gabriele Raino^b^,^c^,^d, Maksym V. Kovalenko^b^,^c^,^d, Dan Oron^a

^aDept. of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, 7610015, Israel

^bLaboratory for Thin Films and Photovoltaics, Empa – Swiss Federal Laboratories For Materials Science and Technology, Switzerland

^cETH Zurich, Laboratory of Inorganic Chemistry, Department of Chemistry & Applied Biosciences, Vladimir-Prelog-Weg, 1, Zürich, Switzerland

^dNational Centre of Competence in Research (NCCR) Catalysis, ETH Zürich, CH-8093 Zürich, Switzerland

Materials for Sustainable Development Conference (MATSUS)
Proceedings of MATSUS Fall 2024 Conference (MATSUSFall24)

#PhotoQD - Photophysics of colloidal quantum dots

Lausanne, Switzerland, 2024 November 12th - 15th

Organizers: Philippe Green and Jannika Lauth

Invited Speaker, Miri Kazes, presentation 119
DOI: https://doi.org/10.29363/nanoge.matsusfall.2024.119
Publication date: 28th August 2024

Colloidal semiconductor nanocrystals have long been considered a promising source of time-correlated and entangled photons via the cascaded emission of multiexcitonic states. The realization and spectroscopy of such cascaded emission, however, is strongly hindered by the highly-efficient, nonradiative Auger process, which renders multiexcitonic states non-emissive. Here we present a room-temperature heralded spectroscopy study of three-photon cascades from triexcitons in giant CsPbBr₃ nanocrystals. Single particle heralded spectroscopy combines the power of the temporal correlation of photon detections with an added information of spectral resolution. In this technique the photoluminescence of a single nanocrystal is collected through a spectrometer coupled to a single-photon avalanche diode array detector, so that each detected photon is time-stamped according to its arrival time, and energy-stamped according to the array pixel it was detected in. This is the first study to fully characterize these types of cascades from quantum dots at room temperature, a task which is difficult due to the significant broadening of emission lines as well as due to temporal fluctuations in the emission. Our results show that the emission pathway of triplets of photons in these particles is dominated by the lowest excited state, and that multiexcitons (biexcitons and triexcitons) are extremely weakly bound, in contrast with low temperature observations. In addition, we aim at elucidating the underlying properties or processes that can lay in the basis of observed differences in blinking statistics and try to correlate these with either intrinsic or surface related properties. This presents interesting opportunities in using emission cascades as deterministic few-photon sources at room temperature that could have important consequences in the development of colloidal quantum light sources.

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