Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence

For the first time, a specific time-delayed peak was registered in the femtosecond transient absorption (TA) spectra of Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS (x~0.5) alloy quantum dots (QDs) doped with Mn<sup>2+</sup>, which was interpreted as the electrochromic Sta...

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Autores principales: Dmitry Cherepanov, Andrei Kostrov, Fedor Gostev, Ivan Shelaev, Mikhail Motyakin, Sergei Kochev, Yuriy Kabachii, Victor Nadtochenko
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Publicado: MDPI AG 2021
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spelling oai:doaj.org-article:74d4483e841c4faab5eb98cc993bfc5b2021-11-25T18:31:38ZUltrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence10.3390/nano111130072079-4991https://doaj.org/article/74d4483e841c4faab5eb98cc993bfc5b2021-11-01T00:00:00Zhttps://www.mdpi.com/2079-4991/11/11/3007https://doaj.org/toc/2079-4991For the first time, a specific time-delayed peak was registered in the femtosecond transient absorption (TA) spectra of Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS (x~0.5) alloy quantum dots (QDs) doped with Mn<sup>2+</sup>, which was interpreted as the electrochromic Stark shift of the band-edge exciton. The time-delayed rise and decay kinetics of the Stark peak in the manganese-doped QDs significantly distinguish it from the kinetics of the Stark peak caused by exciton–exciton interaction in the undoped QDs. The Stark shift in the Mn<sup>2+</sup>-doped QDs developed at a 1 ps time delay in contrast to the instantaneous appearance of the Stark shift in the undoped QDs. Simultaneously with the development of the Stark peak in the Mn<sup>2+</sup>-doped QDs, stimulated emission corresponding to <sup>4</sup>T<sub>1</sub>-<sup>6</sup>A<sub>1</sub> Mn<sup>2+</sup> transition was detected in the subpicosecond time domain. The time-delayed Stark peak in the Mn<sup>2+</sup>-doped QDs, associated with the development of an electric field in QDs, indicates the appearance of charge transfer intermediates in the process of exciton quenching by manganese ions, leading to the ultrafast Mn<sup>2+</sup> excitation. The usually considered mechanism of the nonradiative energy transfer from an exciton to Mn<sup>2+</sup> does not imply the development of an electric field in a QD. Femtosecond TA data were analyzed using a combination of empirical and computational methods. A kinetic scheme of charge transfer processes is proposed to explain the excitation of Mn<sup>2+</sup>. The kinetic scheme includes the reduction of Mn<sup>2+</sup> by a 1Se electron and the subsequent oxidation of Mn<sup>1+</sup> with a hole, leading to the formation of an excited state of manganese.Dmitry CherepanovAndrei KostrovFedor GostevIvan ShelaevMikhail MotyakinSergei KochevYuriy KabachiiVictor NadtochenkoMDPI AGarticlequantum dotfemtosecond transient absorptionstark shiftexcitonChemistryQD1-999ENNanomaterials, Vol 11, Iss 3007, p 3007 (2021)
institution DOAJ
collection DOAJ
language EN
topic quantum dot
femtosecond transient absorption
stark shift
exciton
Chemistry
QD1-999
spellingShingle quantum dot
femtosecond transient absorption
stark shift
exciton
Chemistry
QD1-999
Dmitry Cherepanov
Andrei Kostrov
Fedor Gostev
Ivan Shelaev
Mikhail Motyakin
Sergei Kochev
Yuriy Kabachii
Victor Nadtochenko
Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence
description For the first time, a specific time-delayed peak was registered in the femtosecond transient absorption (TA) spectra of Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS (x~0.5) alloy quantum dots (QDs) doped with Mn<sup>2+</sup>, which was interpreted as the electrochromic Stark shift of the band-edge exciton. The time-delayed rise and decay kinetics of the Stark peak in the manganese-doped QDs significantly distinguish it from the kinetics of the Stark peak caused by exciton–exciton interaction in the undoped QDs. The Stark shift in the Mn<sup>2+</sup>-doped QDs developed at a 1 ps time delay in contrast to the instantaneous appearance of the Stark shift in the undoped QDs. Simultaneously with the development of the Stark peak in the Mn<sup>2+</sup>-doped QDs, stimulated emission corresponding to <sup>4</sup>T<sub>1</sub>-<sup>6</sup>A<sub>1</sub> Mn<sup>2+</sup> transition was detected in the subpicosecond time domain. The time-delayed Stark peak in the Mn<sup>2+</sup>-doped QDs, associated with the development of an electric field in QDs, indicates the appearance of charge transfer intermediates in the process of exciton quenching by manganese ions, leading to the ultrafast Mn<sup>2+</sup> excitation. The usually considered mechanism of the nonradiative energy transfer from an exciton to Mn<sup>2+</sup> does not imply the development of an electric field in a QD. Femtosecond TA data were analyzed using a combination of empirical and computational methods. A kinetic scheme of charge transfer processes is proposed to explain the excitation of Mn<sup>2+</sup>. The kinetic scheme includes the reduction of Mn<sup>2+</sup> by a 1Se electron and the subsequent oxidation of Mn<sup>1+</sup> with a hole, leading to the formation of an excited state of manganese.
format article
author Dmitry Cherepanov
Andrei Kostrov
Fedor Gostev
Ivan Shelaev
Mikhail Motyakin
Sergei Kochev
Yuriy Kabachii
Victor Nadtochenko
author_facet Dmitry Cherepanov
Andrei Kostrov
Fedor Gostev
Ivan Shelaev
Mikhail Motyakin
Sergei Kochev
Yuriy Kabachii
Victor Nadtochenko
author_sort Dmitry Cherepanov
title Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence
title_short Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence
title_full Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence
title_fullStr Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence
title_full_unstemmed Ultrafast Quenching of Excitons in the Zn<sub>x</sub>Cd<sub>1−x</sub>S/ZnS Quantum Dots Doped with Mn<sup>2+</sup> through Charge Transfer Intermediates Results in Manganese Luminescence
title_sort ultrafast quenching of excitons in the zn<sub>x</sub>cd<sub>1−x</sub>s/zns quantum dots doped with mn<sup>2+</sup> through charge transfer intermediates results in manganese luminescence
publisher MDPI AG
publishDate 2021
url https://doaj.org/article/74d4483e841c4faab5eb98cc993bfc5b
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