Solution Precipitation of CdSe Quantum Dots

Abstract

ABSTRACTSynthesis of CdSe quantum dots with a high degree of monodispersity is achieved by nucleation from a supersaturated solution followed by growth to the desired particle size. The effects of temperature on the kinetic mechanisms of nucleation and growth were observed. A reaction vessel equipped with a low thermal mass internal heating element enabled controlled ramping of the solution temperature during the reaction. Nanocrystallite diameter is determined by the reaction time and the solution temperature during particle growth.A method was developed to fabricate ∼1μm thick glass films containing ∼3 vol% CdSe quantum dots. A sol was prepared by mixing a silica organosol with a nanocrystallite dispersion of CdSe and was applied to amorphous quartz substrates by spin-coating. The sols were dried at elevated temperatures in a nitrogen atmosphere. Optical absorbance and fluorescence measurements of the glass film were used to characterize the optical properties of the embedded nanocrystallites. Comparison of the excitonic absorbance of the quantum dot dispersion and the doped glass film shows that particle monodispersity is maintained upon incorporation into the dielectric matrix. Stokes shifts in the band-to-band fluorescence relative to the film absorbance were measured. Shifts in the wavelength of the excitonic absorbance and fluorescence were observed upon incorporation of the quantum dots into the glass film and upon heat treating the glass film to elevated temperatures.