Novel Synthesis and Effective Surface Protection of Air-Stable Luminescent Silicon Nanoparticles

Abstract

Air-stable luminescent silicon nanoparticles with effective surface protection are reported as a quantum dot material with high emission quantum yield. The silicon nanoparticles are prepared by a novel reaction of SiO2 with phenol resins and characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The average particle size of the silicon nanoparticles is controlled by an acid-etching process with hydrofluoric and nitric acids in methanol. The particle size estimated from emission spectra was less than 5 nm. The surfaces of the silicon nanoparticles are protected using a photoassisted reaction with styrene molecules after the acid-etching process. The surface-protected silicon nanoparticles exhibit luminescence at around 650 nm, and their emission quantum yield is estimated to be 55%.

Luminescent Silicon Nanoparticles Surface-Modified with Chiral Molecules

“…This size distribution and average size of silicon nanoparticles with (R)-AOBE is similar to those of silicon nanoparticles with styrene molecules (5.0 nm). Previously, we have reported the quantum size effect on the wavelength of the emission of silicon nanoparticles [16]. The wavelength of the emission for silicon nanoparticles with styrene molecules (average size = 5.0 nm) was found to be 750 nm.…”

“…UV cross-linker, as a photo-assisted reactor (Funakoshi Co.) is used for the photo-chemical reaction of (S)-or (R) -AOBE with silicon surface. Silicon 2.2.1 Acid-etching process of silicon nanoparticles for control of particle size Silicon nanoparticles were obtained using the same method as previous reported [16]. The silicon nanoparticles (4 mg) and methanol (4 ml) were placed into a polypropylene container with the simultaneous addition of 10 mL of 48% HF and 2 mL of 68% nitric acid (HNO 3 ).…”

“…We have reported the formation of the Si-C bond between styrene molecule with vinyl group and silicon, previously. The formation of Si-C bonds on the silicon surface leads to enhancement of the emission quantum yield [16]. Silicon nanoparticles with (S) -or (R) -AOBE also show effective red luminescence.…”

“…Swihart and coworkers have described luminescent silicon nanoparticles covered with polystyrene [15]. We prepared luminescent silicon nanoparticles using photochemical reaction of styrene molecules with Si-H bond on the surface [16]. Recently, surface protection using ionic liquid for prevention of oxidation of silicon nanoparticles has been described [17].…”

Monolayer functionalization of silicon micro and nanowires : towards solar-to-fuel and sensing devices

“…Next to the packing density of the monolayer, the presence of a π-electron system also influences the luminescence properties of the silicon nanoparticles. 124,125 The use of π-conjugated monolayers, e.g., styrene or 1-vinyl naphthalene, not only stabilizes the luminescence properties but also increases the radiation rate compared to 1-decene monolayers. This is opposite to the effect described above for porous silicon substrates, where any conjugated monolayer quenches the photoluminescence.…”