Carrier dynamics in semiconductor quantum dots

Unlike many organic chromofores, semiconductor quantum dots can accomodate multiple excitations. Multiple excitation leads, however, to the opening of new and rapid non-radiative relaxation routes via an Auger mechanism, where an exciton recombines and transfers the energy to a spectator charge. By controlling the composition in a multicomponent ("onion") quantum dot, it is possible to control and utilize this relaxation mechanism.

We have been using a combination of ensemble and single-particle spectroscopy to investigate many unique pohenomena in these particles which exploit enahnced exciton-exciton interactions. These include the first observation of carrier multiplication process in type-II core/shell quantum dot heterostructures and studies elucidating the origin of luminescence interittency in quantum dots. In the past few years we have also been developing quantum spectroscopy - the use of temporal and spectral-temporal photon correlation information as an alternative or an addition to "conventional" time- or frequency- dependent spectroscopy.

We have, more recently, been developing colloidal double quantum dots - two coupled quantum dots packaged into a single nanocrystal, and exhibiting unique properties from two-color antibunching, through controlled blinking to photoluminescence upconversion. See our review on the topic "Colloidal double quantum dots" in Accounts of Chemical Research.

Recent publications:

  1. G. Yang, N. Meir, D. Raanan, D. Oron, “Band gap engineering improves the efficiency of double quantum dot upconversion nanocrystals”, Adv. Funct. Mat. 1900755 (2019).
  2. N. Meir, I. Pinkas, D. Oron, “NIR-to-Visible Upconversion in Quantum Dots via a Ligand Induced Chrage Transfer State”, RSC Advances 9, 12153 (2019)
  3. D. Amgar, G. Yang, R. Tenne, D. Oron, “Higher-order photon correlation as a tool to study exciton dynamics in quasi-2D nanoplatelets”, Nano Letters 19, 8741 (2019).
  4. A. Khan, G. Bertrand, A. Teitelboim, A. Polovitsyn, J. Planelles, J. Climente, I. Juan, D. Oron, I Moreels, “CdSe/CdS/CdTe Core/Barrier/Crown Nanoplatelets: Synthesis, Optoelectronic Properties and Multi-Photon Fluorescence Upconversion”, ACS Nano 14, 4206 (2020).
  5. A. Ludwig, P. Serna, L. Morgenstein, G. Yang, O. Bar-Elli, G. Ortiz, E. Miller, D. Oron, A. Grupi, S. Weiss, A. Triller, “Development of Lipid-Coated Semiconductor Nanosensors for Recording of Membrane Potential in Neurons”, ACS Photonics 7, 1141 (2020).
  6. E. Benjamin, V.J. Yallapragada, D. Amgar, G. Yang, R. Tenne, D. Oron, “Temperature Dependence of Excitonic and Biexcitonic Decay Rates in Colloidal Nanoplatelets by Time-Gated Photon Correlation”, J. Phys. Chem. Lett. 11, 6513 (2020).
  7. G. Yang, M. Kazes, D. Raanan, D. Oron, “Bright Near-Infrared to Visible Upconversion Double Quantum Dots Based on a Type-II/Type-I Heterostructure”, ACS Photonics 8, 1909 (2021).
  8. G. Lubin, R. Tenne, A. Ulku, I. M. Antolovic, S. Burri, S. Karg, V. J. Yallapragada, C. Bruschini, E. Charbon, D. Oron, “Heralded spectroscopy reveals exciton-exciton correlations in single colloidal quantum dots, Nano Lett. 21, 6756 (2021).