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.
- 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).
- 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)
- 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).
- 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).
- 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).
- 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).
- 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).
- 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).