Surface functionalization of hydride-terminated silicon nanocrystals (SiNCs) with dodecene via thermal hydrosilylation has been reexamined. We observed the formation of dodecyl oligomers (n ≤ 4) during the reaction under an argon atmosphere at various predesigned temperatures (100–190 °C). In a comparative study, surface hydrosilylation and ligand oligomerization were found to be more pronounced under air (n ≤ 7) at the same temperatures. These observations strongly suggest that hydrogen abstraction by oxygen accelerates hydrosilylation and generates sufficient silyl radical as initiator to interact with unsaturated bonds, promote chain propagation, and generate ligand oligomers. We further propose that, to inhibit ligand oligomerization and obtain monolayer coverage on SiNC surfaces, it is feasible to apply comparatively low temperatures, inert atmosphere, and dilute ligand concentration during thermal hydrosilylation.

Silicon nanocrystals (SiNCs) have received much attention because of their exquisitely tunable photoluminescent response, biocompatibility, and the promise that they may supplant their CdSe quantum dot counterparts in many practical applications. One attractive strategy that promises to extend and even enhance the utility of SiNCs is their incorporation into NC/polymer hybrids. Unfortunately, methods employed to prepare hybrid materials of this type from traditional compound semiconductor (e.g., CdSe) quantum dots are not directly transferable to SiNCs because of stark differences in surface chemistry. Herein, the preparation of chemically resistant SiNC/polystyrene hybrids exhibiting exquisitely tunable photoluminescence is reported and material processability is demonstrated by preparing micro and nanoscale architectures.

The first solid-state synthesis of diamond structure silicon nanocube structures with edge lengths of 8-15 nm is reported. It is well-established that controlled high-temperature processing of hydrogen silsesquioxane produces exceptionally well-defined pseudospherical silicon nanocrystals. However, only a small number of accounts outlining shape-controlled synthesis have appeared. We report here that, upon prolonged annealing in an oxide matrix, nanocrystal surfaces thermodynamically self-optimize, yielding particles with cubic geometries. Surface functionalization of the resulting nanocubes is readily achieved via thermal hydrosilylation. Discussion will include description of the synthetic procedure, comprehensive material characterization, and the factors that lead to the formation of cubic structures.

Hybrid materials consisting of covalently linked non-toxic silicon nanocrystals and polystyrene are synthesized by J. G. C. Veinot and co-workers. These materials exhibit a strong luminescent response throughout the visible and NIR spectral regions and are chemically resistant. Marrying the properties of silicon nanocrystals with polymers like polystyrene signifi cantly increases their solubility and processability, thus providing the opportunity to fabricate robust nano-and microscale architectures that could fi nd application in a variety of optical applications.

It is well established that controlled high-temperature annealing of hydrogen silsesquioxane leads to the formation of small spherical silicon nanocrystals (~3 nm). The present study outlines an investigation into the influence of annealing time and temperature. After prolonged annealing, crystal surfaces thermodynamically self-optimize to form a variety of faceted structures (e.g., cubic, truncated trigonal and hexagonal structures).