Bright blue emission of synthesized silica nanoparticles conferred by surface defects

Facile synthesis of a monolith of silicon nanocrystal embedded in silica

UV-VISIBLE LUMINESCENCE OF SILICA NANOPARTICLES

Efficiency of concentration photovoltaic cells governed by luminescence processes

The development of multi-junctions III-V semiconductors solar cells, that combine high conversion efficiency (over 40%) and capability of working under high illumination intensity (up to 1000 suns), has stimulated a rapid growth of concentrating photovoltaic (CPV) technology. The performance of these cells is based on the matching between the semiconductors band gap and the solar spectrum so as to optimize the current balancing between the subcells. This requirement is also important in connection with the CPV modules using lenses, mirrors, optical coupling compounds that introduce a wavelength dependent response to the sunlight. Therefore, care must be exercised in designing optimum cells …

Luminescent defects induced by sintering of silica nanoparticles

Optimization of the Optical Components in a Reflective High CPV Module

Thioflavin-T doped silica nanoparticles by basic-catalyzed sol-gel synthesis

We developed a basic-catalyzed sol-gel procedure that allows to synthesize silica nanoparticles functionalized with Thioflavin-T (ThT). During the synthesis, the formation of the doped silica nanoparticles was monitored by absorbance spectra indicating that the catalyst does not cause the total hydroxylation of the dye. Fluorescence measurements carried out on the ThT doped silica nanoparticles proved the attachment of ThT on silica and Raman spectroscopy provided information about the dye structure.

UV-Visible down conversion based on nanosized silica promising for CPV applications

Luminescence properties induced by sintering of silica nanoparticles

The effect of sintering on the optical properties of silica nanoparticles, a mean diameter of ~14 nm, are investigated by absorption and luminescence experiments. The sintering is induced by a thermal treatment of 1000 °C for 272 hours; after that the sample is transparent, and emits a bright luminescence under UV excitation. Time resolved photoluminescence spectra excited by a tunable laser source allows to evidence four bands around 2.0 eV, 2.4 eV, 2.7 eV and 3.4 eV, peculiar to defects induced by the sintering.

Quantum confinement effects observed by the photoluminescence of SiOx/SiO2 multilayers

Spectral and decay features related to the red emission from Si nanocrystals were investigated by time-resolved photoluminescence spectra carried out on SiOx/SiO2 nanosized multilayers. On decreasing the SiOx thickness from 8.4 nm to 2.2 nm this luminescence band exhibits a blue-shift from 1.65 eV to 1.75 eV and its lifetime increases from 12μs to 17 μs. These results are discussed on the basis of previous models proposed in literature and agree with quantum confinement effects arising from differently sized Si nanocrystals in our samples.