title: Stability and fluorescence quantum yield of CdSe-ZnS quantum dots--influence of the thickness of the ZnS shell.
abstract: We investigated the correlation between the thickness of the ZnS shell of CdSe-ZnS quantum dots (QDs), the stability of the particles, and the fluorescence quantum yield. As a measure for stability, a new shell quality test was developed. This test is based on the reaction of the QDs with photochemically formed thiophenol radicals and communicates an imperfect ZnS shell by a rapid and complete loss of fluorescence. The quantum yield increases from less than 5% for unshelled CdSe up to 50%, with an increase in ZnS shell thickness up to 0.6-0.8 nm. At the same time, the particles become significantly more stable, as revealed by the shell test.
authors.affiliation: Federal Institute for Materials Research and Testing, Department I.5, Richard-Willstaetter-Str. 11, 12489 Berlin, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Grabolle
authors.forename: Jan
authors.initials: J
authors.lastname: Ziegler
authors.forename: Alexei
authors.initials: A
authors.lastname: Merkulov
authors.forename: Thomas
authors.initials: T
authors.lastname: Nann
authors.forename: Ute
authors.initials: U
authors.lastname: Resch-Genger
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry*; D002621:Chemistry / Q000379:methods*; D002725:Chloroform; D003460:Crystallization; D005453:Fluorescence; D049449:Luminescence; D053758:Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods; D010636:Phenols / Q000737:chemistry; D045663:Quantum Dots; D018036:Selenium Compounds / Q000737:chemistry*; D012666:Semiconductors; D013050:Spectrometry, Fluorescence / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry; D013440:Sulfides / Q000737:chemistry*; D013997:Time Factors; D017967:Zinc Compounds / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D010636:Phenols; D018036:Selenium Compounds; D013438:Sulfhydryl Compounds; D013440:Sulfides; D017967:Zinc Compounds; C042983:thiophenol; D002725:Chloroform; C058667:cadmium selenide; C031238:zinc sulfide