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.
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, M. Kazes, D. Oron, “Chiral 2D Colloidal Semiconductor Quantum Wells”, Adv. Funct. Mat. 1802012 (2018).
- O. Bar-Elli, D. Steinitz, G. Yang, R. Tenne, A. Ludwig, Y. Kuo, A. Triller, S. Weiss, D. Oron, “Rapid voltage sensing with single nanorods via the quantum confined Stark effect”, ACS Photonics 5, 2860 (2018).
- 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).
- 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).