Strong photoluminescence enhancement from colloidal quantum dot near silver nano-island films.

We present the fabrication and optical investigation of highly random self-assembled, nano-scale films, probing their influence on the luminescence properties of near surface CdSe/ZnS colloidal quantum dots. When compared to quantum dots distributed on unstructured quartz substrates, the average luminescence intensity is found to be enhanced by a factor of 160×. The silver nanoparticles are prepared using slow thermal evaporation on quartz substrates and post-deposition annealing to produce a randomly-arranged layer of smooth nano-islands. Clear polarization dependent hot spots are observed. Such hot spots deliver a maximal enhancement of the emission intensity of 240× and have a spatial density of (0.050±0.002) μm( -2). The results show that silver nano-island films strongly enhance the optical efficiency of near quantum dots emitters.