title: Gradient CdSe/CdS Quantum Dots with Room Temperature Biexciton Unity Quantum Yield.
abstract: Auger recombination is a major limitation for the fluorescent emission of quantum dots (QDs). It is the main source of QDs fluorescence blinking at the single-particle level. At high-power excitation, when several charge carriers are formed inside a QD, Auger becomes more efficient and severely decreases the quantum yield (QY) of multiexcitons. This limits the efficiency and the use of colloidal QDs in applications where intense light output is required. Here, we present a new generation of thick-shell CdSe/CdS QDs with dimensions >40 nm and a composition gradient between the core and the shell that exhibits 100% QY for the emission of both the monoexciton and the biexciton in air and at room temperature for all the QDs we have observed. The fluorescence emission of these QDs is perfectly Poissonian at the single-particle level at different excitation levels and temperatures, from 30 to 300 K. In these QDs, the emission of high-order (>2) multiexcitons is quite efficient, and we observe white light emission at the single-QD level when high excitation power is used. These gradient thick shell QDs confirm the suppression of Auger recombination in gradient core/shell structures and help further establish the colloidal QDs with a gradient shell as a very stable source of light even under high excitation.
authors.affiliation: †Laboratoire de Physique et d'Etude des Matériaux (LPEM), PSL Research University, ESPCI-ParisTech, 10 rue Vauquelin, F-75231 Paris Cedex 5, France.|‡UMR 8213, CNRS, F-75005 Paris, France.|§UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Nasilowski
authors.affiliation: †Laboratoire de Physique et d'Etude des Matériaux (LPEM), PSL Research University, ESPCI-ParisTech, 10 rue Vauquelin, F-75231 Paris Cedex 5, France.|‡UMR 8213, CNRS, F-75005 Paris, France.|§UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris, France.
authors.forename: Piernicola
authors.initials: P
authors.lastname: Spinicelli
authors.affiliation: ⊥Laboratoire Photonique et Nanostructures, CNRS, 91460 Marcoussis, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Patriarche
authors.affiliation: †Laboratoire de Physique et d'Etude des Matériaux (LPEM), PSL Research University, ESPCI-ParisTech, 10 rue Vauquelin, F-75231 Paris Cedex 5, France.|‡UMR 8213, CNRS, F-75005 Paris, France.|§UPMC Univ Paris 06, Sorbonne Universités, F-75005 Paris, France.
authors.forename: Benoît
authors.initials: B
authors.lastname: Dubertret
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D005453:Fluorescence; D045663:Quantum Dots / Q000737:chemistry*; D018036:Selenium Compounds / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; D013440:Sulfides; C034939:cadmium sulfide; C058667:cadmium selenide
keywords: Quantum dots; biexciton; blinking; gradient core/shell; multiexcitons; quantum yield