Effect of high-pressure water-vapor annealing on energy transfer in dye-impregnated porous silicon

application/pdfArticleWe have studied the effect of high-pressure water-vapor annealing (HWA) on the excitation energy transfer from Si nanocrystals to dye molecules in porous Si layers. Efficient photoluminescence, originating from both RhB molecules and Si nanocrystals, was observed. The behavior of the polarization memory of the photoluminescence showed the presence of energy transfer from the surface-passivated Si nanocrystals to RhB molecules. The fact that HWA, which is an effective method to stabilize and enhance the emission from Si nanocrystals in porous Si, does not suppress the energy transfer is an important result since it makes possible the realization of stable Si/dye-nanocomposite functional devices.journal articl

Energy transfer in porous-silicon/laser-dye composite evidenced by polarization memory of photoluminescence

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Multiple energy transfer in porous silicon/Rh6G/RhB nanocomposite evidenced by photoluminescence and its polarization memory

application/pdfArticlePorous silicon (PSi)– laser dye composites were obtained by simply immersing PSi in ethanolic solutions of rhodamine 6G (Rh6G), rhodamine B (RhB), and RhB:Rh6G mixture. Partially oxidized PSi was also used as a host matrix. Fourier transform infrared spectroscopy suggests that the dye molecules fully penetrate into the porous matrix. Efficient photoluminescence (PL) was observed in all nanocomposites. The study of the polarization memory of PL provides a clear evidence for the presence of energy transfer from PSi to Rh6G molecules. The energy transfer was found more efficient in oxidized PSi. In RhB:Rh6G/PS composite, energy transfer from Rh6G molecules to RhB molecules was demonstrated. Rh6G molecules play the role of an intermediate radiative center in the excitation energy transfer from PSi to RhB molecules.journal articl

Electroluminescence stabilization of nanocrystalline porous silicon diodes

NRC publication: Ye

First-Principles Study of the Band Gap Structure of Oxygen-Passivated Silicon Nanonets

A net-like nanostructure of silicon named silicon nanonet was designed and oxygen atoms were used to passivate the dangling bonds. First-principles calculation based on density functional theory with the generalized gradient approximation (GGA) were carried out to investigate the energy band gap structure of this special structure. The calculation results show that the indirect–direct band gap transition occurs when the nanonets are properly designed. This band gap transition is dominated by the passivation bonds, porosities as well as pore array distributions. It is also proved that Si–O–Si is an effective passivation bond which can change the band gap structure of the nanonets. These results provide another way to achieve a practical silicon-based light source