Controlled insertion of electronic states within the band gap of semiconductor nanocrystals (NCs) is a powerful tool for tuning their physical properties. One compelling example is II-VI NCs incorporating heterovalent coinage metals in which hole capture produces acceptor-bound excitons. To date, the opposite donor-bound exciton scheme has not been realized because of the unavailability of suitable donor dopants. Here, we produce a model system for donor-bound excitons in CdSeS NCs engineered with sulfur vacancies (VS) that introduce a donor state below the conduction band (CB), resulting in long-lived intragap luminescence. VS-localized electrons are almost unaffected by trapping, and suppression of thermal quenching boosts the emission efficiency to 85%. Magneto-optical measurements indicate that the VS are not magnetically coupled to the NC bands and that the polarization properties are determined by the spin of the valence-band photohole, whose spin flip is massively slowed down due to suppressed exchange interaction with the donor-localized electron.

Carulli, F., Pinchetti, V., Zaffalon, M., Camellini, A., Rotta Loria, S., Moro, F., et al. (2021). Optical and Magneto-Optical Properties of Donor-Bound Excitons in Vacancy-Engineered Colloidal Nanocrystals. NANO LETTERS, 21(14), 6211-6219 [10.1021/acs.nanolett.1c01818].

Optical and Magneto-Optical Properties of Donor-Bound Excitons in Vacancy-Engineered Colloidal Nanocrystals

Carulli, Francesco
Primo
;
Pinchetti, Valerio;Zaffalon, Matteo L;Moro, Fabrizio;Fanciulli, Marco;Meinardi, Francesco;Brovelli, Sergio
Ultimo
2021

Abstract

Controlled insertion of electronic states within the band gap of semiconductor nanocrystals (NCs) is a powerful tool for tuning their physical properties. One compelling example is II-VI NCs incorporating heterovalent coinage metals in which hole capture produces acceptor-bound excitons. To date, the opposite donor-bound exciton scheme has not been realized because of the unavailability of suitable donor dopants. Here, we produce a model system for donor-bound excitons in CdSeS NCs engineered with sulfur vacancies (VS) that introduce a donor state below the conduction band (CB), resulting in long-lived intragap luminescence. VS-localized electrons are almost unaffected by trapping, and suppression of thermal quenching boosts the emission efficiency to 85%. Magneto-optical measurements indicate that the VS are not magnetically coupled to the NC bands and that the polarization properties are determined by the spin of the valence-band photohole, whose spin flip is massively slowed down due to suppressed exchange interaction with the donor-localized electron.
Articolo in rivista - Articolo scientifico
bound exciton; electronic doping; magneto-optics; nanocrystal quantum dots; spectro-electrochemistry; sulfur vacancy;
English
14-lug-2021
2021
21
14
6211
6219
open
Carulli, F., Pinchetti, V., Zaffalon, M., Camellini, A., Rotta Loria, S., Moro, F., et al. (2021). Optical and Magneto-Optical Properties of Donor-Bound Excitons in Vacancy-Engineered Colloidal Nanocrystals. NANO LETTERS, 21(14), 6211-6219 [10.1021/acs.nanolett.1c01818].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/320162
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