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Fine structure of nearly isotropic bright excitons in InP/ZnSe colloidal quantum dots

Brodu, Annalisa, Chandrasekaran, Vigneshwaran, Scarpelli, Lorenzo, Buhot, Jonathan, Masia, Francesco ORCID:, Ballottin, Mariana V., Severijnen, Marion, Tessier, Mickael D., Dupont, Dorian, Rabouw, Freddy T., Christianen, Peter C. M., de Mello Donega, Celso, Vanmaekelbergh, Daniel, Langbein, Wolfgang ORCID: and Hens, Zeger 2019. Fine structure of nearly isotropic bright excitons in InP/ZnSe colloidal quantum dots. Journal of Physical Chemistry Letters 10 (18) , pp. 5468-5475. 10.1021/acs.jpclett.9b01824

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The fine structure of exciton states in colloidal quantum dots (QDs) results from the compound effect of anisotropy and electron-hole exchange. By means of single-dot photoluminescence spectroscopy, we show that the emission of photo-excited InP/ZnSe QDs originates from radiative recombination of such fine-structure exciton states. Depending on the excitation power, we identify a bright exciton doublet, a trion singlet and a biexciton doublet line that all show a pronounced polarization. Fluorescence line narrowing spectra of an ensemble of InP/ZnSe QDs in magnetic fields demonstrate that the bright exciton effectively consists of three states. The Zeeman splitting of these states is well described by an isotropic exciton model, where the fine structure is dominated by electron-hole exchange and shape anisotropy only leads to a minor splitting of the F=1 triplet. We argue that excitons in InP-based QDs are nearly isotropic because the particular ratio of light and heavy hole masses in InP makes the exciton fine structure insensitive to shape anisotropy.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Publisher: American Chemical Society
ISSN: 1948-7185
Date of First Compliant Deposit: 22 August 2019
Date of Acceptance: 19 August 2019
Last Modified: 09 Nov 2023 22:29

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