Colloidal CdSe/CdS dot-in-plate nanocrystals with 2D-polarized emission.
We report the synthesis and properties of a novel class of nanocrystals with mixed dimensionality: a dot-in-plate core/shell nanostructure. This system was synthesized by growing a flat, disk-shaped, CdS shell on spherical CdSe cores. The anisotropic pressure induced by the shell drastically splits the first exciton fine structure in two: the "heavy hole" and "light hole" states become separated by up to 65 meV. As a result, these nanocrystals exhibit an emission strongly polarized in two dimensions, in the plane perpendicular to the wurtzite crystal c axis. We use polarization measurements on single nanocrystals and ensemble anisotropy studies to confirm the nature and position of the excitonic energy levels. These nanocrystals orient spontaneously when evaporated on a substrate, enabling a precise control of the orientation of their emission dipole.
Laboratoire Physique et Etude des Matériaux, ESPCI/CNRS/UPMC UMR 8213, 10, rue Vauquelin, 75005 Paris, France.
Elsa
E
Cassette
Benoît
B
Mahler
Jean-Michel
JM
Guigner
Gilles
G
Patriarche
Benoît
B
Dubertret
Thomas
T
Pons
D019187:Cadmium Compounds / Q000737:chemistry*; D003102:Colloids / Q000737:chemistry; D008027:Light; D008422:Materials Testing; D008968:Molecular Conformation; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size; D045663:Quantum Dots; D012031:Refractometry / Q000295:instrumentation*; D012542:Scattering, Radiation; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D013499:Surface Properties
D019187:Cadmium Compounds; D003102:Colloids; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C058667:cadmium selenide