Excitons and Multeixcitons in Quantum Dot Molecules
Uri Banin a
a The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
Proceedings of Emerging Light Emitting Materials 2025 (EMLEM25)
La Canea, Greece, 2025 October 8th - 10th
Organizers: Maksym Kovalenko and Grigorios Itskos
Invited Speaker, Uri Banin, presentation 035
Publication date: 17th July 2025

Colloidal semiconductor Quantum Dots (QDs), often considered as artificial atoms, have reached an exquisite level of control, alongside gaining fundamental understanding of their size, composition and surface-controlled properties, as recognized by the Nobel prize in Chemistry 2023. Their tuned characteristics and scalable bottom-up synthesis accompanied by the applicability of solution based manipulation, have led to their wide implementation in displays, lasers, light emitting diodes, single photon sources, photodetectors and more.

For the next step towards enhancing functionalities of quantum dots, inspired by molecular chemistry, we introduce the controlled linking and fusion of two core/shell quantum dots creating an artificial molecule manifesting two coupled emitting centers.1 Accordingly, the coupled colloidal quantum dot molecules (CQDMs) present novel behaviors differing than their quantum dot building blocks. Utilizing single particle spectroscopy, especially a version of heralded spectroscopy, we distinguish between localized versus segregated multiexciton states. 2, 3  Furthermore, this also affects the multiexciton dynamics in CQDMs compared with the monomer QDs. Moreover, such CQDMs open the path to a novel electric field induced instantaneous color switching effect, allowing color tuning without intensity loss, that is not possible in single quantum dots.4 All in all, such quantum dot molecules, manifesting two coupled emission centers, may be tailored to emit distinct colors, opening the path for sensitive field sensing and color switchable devices such as a novel pixel design for displays or an electric field color tunable single photon source.

[1] J. Cui, Y.E. Panfil, S. Koley, D. Shamalia, N. Waiskopf, S. Remennik, I. Popov, M. Oded, U. Banin, “Colloidal Quantum Dot Molecules Manifesting Quantum Coupling at Room Temperature” Nature Comm 10, 5401 (2019)

[2] Somnath Koley, Jiabin Cui, Yossef. E. Panfil, Yonatan Ossia, Adar Levi, Einav Scharf, Lior Verbitsky and Uri Banin, “Photon Correlations in Colloidal Quantum Dot Molecules Controlled by the Neck Barrier” Matter 5, 3997-4014 (2022)

[3] N. Frenkel, E. Scharf, G. Lubin, A. Levi, Y. E. Panfil, Y. Ossia, J. Planelles, J. I. Climente, U. Banin, and Dan Oron, “Two Biexciton Types Coexisting in Coupled Quantum Dot Molecules.” ACS Nano 17, 14990-15000 (2023)

[4]Y. Ossia, A. Levi, Y.E. Panfil, S. Koley, E, Scharf, N. Chefetz, S. Remennik, A. Vakahi, U. Banin, “Electric field induced color switching in colloidal quantum dot molecules at room temperature” Nature Materials 22, 1210-1217 (2023)

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