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arXiv · 2512.13867

Vanishing quantum confinement enables bright and thermally excited multi-carrier emission from semiconductor nanocrystals

Tjom Arens·Sander J. W. Vonk·A. Willem Vlasblom·Margarita Samoli·Daniel Vanmaekelbergh·Pieter Geiregat·Zeger Hens·Freddy T. Rabouw
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Abstract

Recently, nanocrystals in the regime of vanishing quantum confinement-termed bulk nanocrystals (BNCs)-have demonstrated remarkable optical gain characteristics. While their high-power lasing performance was demonstrated convincingly, the photophysics at low and intermediate powers-where charge-carrier populations are discrete-remain unexplored. Using single-photon avalanche diode (SPAD) array technology, we resolve the dynamics and energetics of six multi-carrier excited states in individual CdSe/CdS core/shell BNCs, containing up to four electrons and two holes. Each state exhibits bimodal emission, indicative of thermal equilibrium between closely spaced electron and hole levels, confirmed via temperature-dependent single-particle measurements. Quantification of radiative and nonradiative decay channels reveals strongly suppressed Auger recombination through both the negative- and positive-trion pathways. We present a model that combines statistical scaling of rate constants with Fermi-Dirac thermal occupations of electron and hole levels, bridging the transitional regime between quantum-confined and bulk nanocrystals, and providing a comprehensive framework for understanding this emerging class of materials.

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Tjom Arens, Sander J. W. Vonk, A. Willem Vlasblom, Margarita Samoli, Daniel Vanmaekelbergh, Pieter Geiregat, Zeger Hens, Freddy T. Rabouw. 2025-12-15. Vanishing quantum confinement enables bright and thermally excited multi-carrier emission from semiconductor nanocrystals. https://doi.org/10.1021/acsnano.5c19908

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