Highly luminescent water-soluble ZnSe nanocrystals and their incorporation in a glass matrix

Post-preparative white light irradiation causes thiol-stabilized ZnSe nanocrystals (NCs) dispersed in water to become photoluminescent. The reported photoluminescence efficiency and peak wavelength are 25–30% and ca. 390 nm, respectively. We have found that through a judicious choice of irradiation conditions, especially the irradiation wavelength and intensity, the solution pH, and the NC concentration, we can increase the emission efficiency to 50% with a peak wavelength in the visible region (405–435 nm). These improvements were achieved through efficient formation of a thick ZnS shell (more than 1 nm) around the ZnSe core (2–3 nm in diameter) enabled by the generation of sulfur ions at an appropriate speed via the photodecomposition of a thiol stabilizer. To make them more suitable for application, we then incorporated the prepared NCs into a glass matrix, taking advantage of their water solubility through a sol–gel method. The prepared glass had an efficiency of more than 20% without deterioration of the photoluminescent spectral shape of the initial solution.