Engineering Bicolor Emission in 2D Core/Crown CdSe/CdSe1-xTex Nanoplatelet Heterostructures Using Band-offset Tuning

Marion Dufour1, Violette Steinmetz2, Eva Izquierdo1, Thomas Pons1, Nicolas Lequeux1, Emmanuel
Lhuillier2, Laurent Legrand2, Maria Chamarro2, Thierry Barisien2, Sandrine Ithurria1*
1Laboratoire de Physique et d’Etude des Matériaux, PSL Research University, CNRS UMR 8213, ESPCI
Paris, 10 rue Vauquelin, 75005 Paris, France.
2Sorbonne Universités, UPMC Univ. Paris 06, CNRS-UMR 7588, Institut des Nanosciences de Paris, 4
place Jussieu, 75005 Paris, France
Abstract : Colloidal 2D nanoplatelets (NPLs) are a class of nanoparticles that offer the possibility of forming
two types of heterostructures, by growing either in the confined direction or perpendicular to the confined
direction, called core/crown NPLs. Here, we demonstrate that bicolor emission can be obtained from 2D
NPLs with a core/crown geometry. To date, for CdSe/CdTe NPLs with type-II band alignment, only charge
transfer emission has been observed due to the very fast (<ps) transfer of the electrons toward the CdSe core.
Here, we show that using CdSe1-xTex alloys crowned with the right composition and lateral extension
enables the observation of bicolor emission at the single-particle level. One source of emission originates
from recombination at the core/crown interface (Xint), and the other emission source originates from direct
recombination in the crown (Xcrown). This crown emission, which is nonvisible in pure CdSe/CdTe core
crown NPLs, results from the large binding energy compared to the reduced conduction band offset existing
in the alloy with intermediate (60%) Te content. These observations are only made possible by the 2D
geometry of the NPLs.
Keywords : nanoplatelets, cadmium chalcogenides, bicolor emission, colloidal heterostructure, exciton
*To whom correspondence should be sent : sandrine.ithurria (arobase)

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