Fabrication and optical properties of thin silica-coated CdSe/ZnS quantum dots



We demonstrate the fabrication of thin silica-coated CdSe/ZnS colloidal quantum dots using a reverse microemulsion method. Spherical particles of <20 nm diameter with a single dot in the centre of a thin silica shell of good morphology are achieved, promising for biophotonic applications where hydrophilic bio-compatible and small luminescent nanoparticles are needed. We characterize the spectrally- and time-resolved photoluminescence of these silica-coated dots, from which we identify the influence of each step of the coating procedure on their emission quantum yield. Optimization of the growth parameters eventually results in a less than two-fold reduction of the quantum yield after silica-coating.