Colloidal CdSe nanocrystals (NCs) overcoated with an ultrathick CdS shell, also known as dot-in-bulk (DiB) structures, can support two types of excitons, one of which is core-localized and the other, shell-localized. In the case of weak "sub-single-exciton" pumping, emission alternates between the core-and shell-related channels, which leads to two-color light. This property makes these structures uniquely suited for a variety of photonic applications as well as ideal model systems for realizing complex excitonic quasi-particles that do not occur in conventional core/shell NCs. Here, we show that the DiB design can enable an unusual regime in which the same long-lived resident electron can endow trionlike characteristics to either of the two excitons of the DiB NC (core-or shell-based). These two spectrally distinct trion states are apparent in the measured photoluminescence (PL) and spin dynamics of core and shell excitons conducted over a wide range of temperatures and applied magnetic fields. Low-Temperature PL measurements indicate that core-and shell-based trions are characterized by a nearly ideal (â 100%) emission quantum yield, suggesting the strong suppression of Auger recombination for both types of excitations. Polarization-resolved PL experiments in magnetic fields of up to 60 T reveal that the core-and the shell-localized trions exhibit remarkably similar spin dynamics, which in both cases are controlled by spin-flip processes involving a heavy hole.

Pinchetti, V., Shornikova, E., Qiang, G., Bae, W., Meinardi, F., Crooker, S., et al. (2019). Dual-emitting dot-in-bulk cdse/cds nanocrystals with highly emissive core-and shell-based trions sharing the same resident electron. NANO LETTERS, 19(12), 8846-8854 [10.1021/acs.nanolett.9b03676].

Dual-emitting dot-in-bulk cdse/cds nanocrystals with highly emissive core-and shell-based trions sharing the same resident electron

Pinchetti, Valerio
Primo
;
Meinardi, Francesco;Brovelli, Sergio
Ultimo
2019

Abstract

Colloidal CdSe nanocrystals (NCs) overcoated with an ultrathick CdS shell, also known as dot-in-bulk (DiB) structures, can support two types of excitons, one of which is core-localized and the other, shell-localized. In the case of weak "sub-single-exciton" pumping, emission alternates between the core-and shell-related channels, which leads to two-color light. This property makes these structures uniquely suited for a variety of photonic applications as well as ideal model systems for realizing complex excitonic quasi-particles that do not occur in conventional core/shell NCs. Here, we show that the DiB design can enable an unusual regime in which the same long-lived resident electron can endow trionlike characteristics to either of the two excitons of the DiB NC (core-or shell-based). These two spectrally distinct trion states are apparent in the measured photoluminescence (PL) and spin dynamics of core and shell excitons conducted over a wide range of temperatures and applied magnetic fields. Low-Temperature PL measurements indicate that core-and shell-based trions are characterized by a nearly ideal (â 100%) emission quantum yield, suggesting the strong suppression of Auger recombination for both types of excitations. Polarization-resolved PL experiments in magnetic fields of up to 60 T reveal that the core-and the shell-localized trions exhibit remarkably similar spin dynamics, which in both cases are controlled by spin-flip processes involving a heavy hole.
Articolo in rivista - Articolo scientifico
charged excitons/trions; core/shell heterostructures; dual emission; Nanocrystals; spin dynamics;
English
2019
19
12
8846
8854
none
Pinchetti, V., Shornikova, E., Qiang, G., Bae, W., Meinardi, F., Crooker, S., et al. (2019). Dual-emitting dot-in-bulk cdse/cds nanocrystals with highly emissive core-and shell-based trions sharing the same resident electron. NANO LETTERS, 19(12), 8846-8854 [10.1021/acs.nanolett.9b03676].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/254711
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