Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots

Annalisa Brodu; Vigneshwaran Chandrasekaran; Lorenzo Scarpelli; Jonathan Buhot; Francesco Masia; Mariana V. Ballottin; Marion Severijnen; Mickaël D. Tessier; Dorian Dupont; Freddy T. Rabouw; Peter C.M. Christianen; Celso De Mello Donega; Daniël Vanmaekelbergh; Wolfgang Langbein; Zeger Hens

doi:10.1021/acs.jpclett.9b01824

Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots

Annalisa Brodu
, Vigneshwaran Chandrasekaran
, Lorenzo Scarpelli
, Jonathan Buhot
, Francesco Masia
, Mariana V. Ballottin
, Marion Severijnen
, Mickaël D. Tessier
, Dorian Dupont
, Freddy T. Rabouw
, Peter C.M. Christianen
, Celso De Mello Donega
, Daniël Vanmaekelbergh^*
, Wolfgang Langbein
, Zeger Hens

^*Corresponding author for this work

Research output: Contribution to journal › Article › Academic › peer-review

Abstract

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 photoexcited 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 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 leads to only 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.

Original language	English
Pages (from-to)	5468-5475
Number of pages	8
Journal	Journal of Physical Chemistry Letters
Volume	10
Issue number	18
DOIs	https://doi.org/10.1021/acs.jpclett.9b01824
Publication status	Published - 19 Sept 2019

Funding

Z.H., D.V., and W.L. acknowledge support from the European Commission via the Marie-Sklodowska Curie action Phonsi (H2020-MSCA-ITN-642656). Z.H. acknowledges support by SIM-Flanders (SBO-QDOCCO), FWO-Vlaanderen (Research Project 17006602), and Ghent University (GOA 01G01019). F.T.R. is supported by NWO Veni Grant 722.017.002 and by The Netherlands Center for Multiscale Catalytic Energy Conversion (MCEC), an NWO Gravitation program funded by the Ministry of Education, Culture and Science of the government of The Netherlands. F.M. acknowledges the Ser Cymru II programme (Case ID 80762-CU-148) which is partly funded by Cardiff University and the European Regional Development Fund through the Welsh Government. This work was supported by HFML-RU/FOM, member of the European Magnetic Field Laboratory (EMFL).

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10.1021/acs.jpclett.9b01824

broduFinal published version, 3.14 MBLicence: Taverne

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Brodu, A., Chandrasekaran, V., Scarpelli, L., Buhot, J., Masia, F., Ballottin, M. V., Severijnen, M., Tessier, M. D., Dupont, D., Rabouw, F. T., Christianen, P. C. M., De Mello Donega, C., Vanmaekelbergh, D., Langbein, W., & Hens, Z. (2019). Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots. Journal of Physical Chemistry Letters, 10(18), 5468-5475. https://doi.org/10.1021/acs.jpclett.9b01824

@article{7eac3b99eb714d088e3b898f5b3acf9c,

title = "Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots",

abstract = "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 photoexcited 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 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 leads to only 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.",

author = "Annalisa Brodu and Vigneshwaran Chandrasekaran and Lorenzo Scarpelli and Jonathan Buhot and Francesco Masia and Ballottin, \{Mariana V.\} and Marion Severijnen and Tessier, \{Micka{\"e}l D.\} and Dorian Dupont and Rabouw, \{Freddy T.\} and Christianen, \{Peter C.M.\} and \{De Mello Donega\}, Celso and Dani{\"e}l Vanmaekelbergh and Wolfgang Langbein and Zeger Hens",

year = "2019",

month = sep,

day = "19",

doi = "10.1021/acs.jpclett.9b01824",

language = "English",

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Brodu, A, Chandrasekaran, V, Scarpelli, L, Buhot, J, Masia, F, Ballottin, MV, Severijnen, M, Tessier, MD, Dupont, D, Rabouw, FT, Christianen, PCM, De Mello Donega, C , Vanmaekelbergh, D, Langbein, W & Hens, Z 2019, 'Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots', Journal of Physical Chemistry Letters, vol. 10, no. 18, pp. 5468-5475. https://doi.org/10.1021/acs.jpclett.9b01824

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T1 - Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots

AU - Brodu, Annalisa

AU - Chandrasekaran, Vigneshwaran

AU - Scarpelli, Lorenzo

AU - Buhot, Jonathan

AU - Masia, Francesco

AU - Ballottin, Mariana V.

AU - Severijnen, Marion

AU - Tessier, Mickaël D.

AU - Dupont, Dorian

AU - Rabouw, Freddy T.

AU - Christianen, Peter C.M.

AU - De Mello Donega, Celso

AU - Vanmaekelbergh, Daniël

AU - Langbein, Wolfgang

AU - Hens, Zeger

PY - 2019/9/19

Y1 - 2019/9/19

N2 - 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 photoexcited 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 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 leads to only 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.

AB - 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 photoexcited 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 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 leads to only 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.

UR - https://www.scopus.com/pages/publications/85072380089

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DO - 10.1021/acs.jpclett.9b01824

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SN - 1948-7185

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SP - 5468

EP - 5475

JO - Journal of Physical Chemistry Letters

JF - Journal of Physical Chemistry Letters

IS - 18

ER -

Fine Structure of Nearly Isotropic Bright Excitons in InP/ZnSe Colloidal Quantum Dots

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