Carboxyl functionalization of ultrasmall luminescent silicon nanoparticles through thermal hydrosilylation (original) (raw)

Solution Synthesis of Ultrastable Luminescent Siloxane-Coated Silicon Nanoparticles

Nano Letters, 2004

Silicon nanoparticles (NPs) of ∼4.5(1.10) nm from a room-temperature solution route are terminated by a silanization method for the first time. Energy-selected emission is observed, consistent with the distribution of sizes obtained by this route. The NPs are photochemically stable in nonpolar organic solvents and when exposed to air/water under ambient conditions for up to 1 year. The nanoparticles were characterized by TEM, HRTEM, EDX, SAED, FTIR, 1 H/ 13 C NMR, UV−vis, and photoluminescence (PL) spectroscopy.

Silica encapsulation of luminescent silicon nanoparticles: stable and biocompatible nanohybrids

Journal of Nanoparticle Research, 2012

This article presents a process for surface coating and functionalization of luminescent silicon nanoparticles. The particles were coated with silica using a microemulsion process that was adapted to the fragile silicon nanoparticles. The as-produced coreshell particles have a mean diameter of 35 nm and exhibit the intrinsic photoluminescence of the silicon core. The silica layer protects the core from aqueous oxidation for several days, thus allowing the use of the nanoparticles for biological applications. The nanoparticles were further coated with amines and functionalized with polyethylene glycol chains and the toxicity of the particles has been evaluated at the different stages of the process. The core-shell nanoparticles exhibit no acute toxicity towards lung cells, which is promising for further development.

Efficient Surface Grafting of Luminescent Silicon Quantum Dots by Photoinitiated Hydrosilylation

Langmuir, 2005

We suggest a method for efficient (high-coverage) grafting of organic molecules onto photoluminescent silicon nanoparticles. High coverage grafting was enabled by use of a modified etching process that produces a hydrogen-terminated surface on the nanoparticles with very little residual oxygen and by carefully excluding oxygen during the grafting process. It had not previously been possible to produce such a clean H-terminated surface on free silicon nanoparticles or, subsequently, to produce grafted particles without significant surface oxygen. This allowed us to (1) prepare air-stable green-emitting silicon nanoparticles, (2) prepare stable dispersions of grafted silicon nanoparticles in a variety of organic solvents from which particles can readily be precipitated by addition of nonsolvent, dried, and redispersed, (3) separate these nanoparticles by size (and therefore emission color) using conventional chromatographic methods, (4) protect the particles from chemical attack and photoluminescence quenching, and (5) provide functional groups on the particle surface for further derivatization. We also show, using 1 H NMR, that the photoinitiated hydrosilylation reaction does not specifically graft the terminal carbon atom to the surface but that attachment at both the first and second atom occurs 10.

Preparation of Luminescent Silicon Nanoparticles: A Novel Sonochemical Approach

Currently porous silicon has been attracted a great deal of attention because of its novel optoelectronic properties due to visible light emission. The electronic properties of bulk silicon cannot explain the above phenomenon, as silicon has the indirect band gap of 1.1 eV. In early investigations, the predominant view was that the surface structure, especially surface defects, controlled the luminescence properties. 2 However, recent work on quantum dot particles has suggested that the visible luminescence of porous silicon results from the quantum confinement of electron-hole pairs and controls the band gap widening into the visible range. 3 Therefore, the processing of silicon nanoparticles (qparticles) has generated extensive speculation over the possibilities of new applications for silicon. In this paper we describe a novel sonochemical procedure for generating porous silicon nanoparticles in high yields that exhibit luminescence, attributed to quantum confinement effects.