Xylene-Capped Luminescent Silicon Nanocrystals: Evidence of Supramolecular Bonding

Abstract

We report capping of silicon (Si) nanocrystals (NCs) via xylene attachment to the surface of oxide etched, luminescent, core/shell nanostructures of Si/Si-oxide in colloidal suspension. The core/shell nanostructures of Si/Si-oxide are formed by controlled oxidation of mechanically milled crystalline Si, which is subsequently etched in aqueous hydrofluoric acid to remove the oxide shell. Xylene attachment is confirmed by peak splitting and shifting in the Fourier transform infrared spectra for the xylene-treated samples in colloidal suspensions as well as for samples deposited on solid substrates like ZnSe. Structural investigations and spectroscopic evidence suggest that capping of Si NCs is associated with the formation of weak supramolecular bonds with the antibonding electrons of xylene. Therefore, we successfully achieve the much desired attachment of methyl groups onto the surface of luminescent Si NCs by a very weak physical bond with minimal modification of the surface chemistry of the NCs.

Precise Tuning of the Thickness and Optical Properties of Highly Stable 2D Organometal Halide Perovskite Nanosheets through a Solvothermal Process and Their Applications as a White LED and a Fast Photodetector

“…The CIE coordinates of the fabricated white LED closely match with the pure white light (0.33, 0.33). The performance and color purity of the orange luminescent perovskite-coated white LED are comparable or better than the other reported orange luminescent phosphor-coated white LEDs using carbon dots, silicon dots, and other 2D materials. − Hence, the mixed halide perovskite can be considered as a promising candidate for the high color quality, low-cost white light production, and in the solid-state lighting field. The operational stability of fabricated LED is measured up to 7 h of continuous operation at 2.35 V. It is observed that the intensity of blue emission from LED chip (encapsulated) is nearly unchanged, while the intensity of yellow emission from MAPbBr 1 I 2 is decreased by about 20%, as shown in Figure S8b (Supporting Information).…”

Surface-engineered silicon nanocrystals

“…32 Post-synthesis surface engineering of Si-ncs has so far largely relied on traditional or enhanced (e.g. thermally, by illumination) solution chemistry 33,73,[75][76][77][78][79][80][81] and only very recently, alternative approaches have made signicant and very promising advances. 17,22,23,75,[82][83][84][85][86][87][88][89] The solution chemistry approach is generally achieved through the realization of a chemically active surface (e.g.…”

Fluorescent nanomaterial-derived white light-emitting diodes: what's going on

“…In recent times, luminescent silicon QDs (Si QDs) have been considered highly attractive for LEDs because they are considered to be nontoxic, photostable, conductive, and involve environmental-friendly nanomanufacturing. [115][116][117] Towards this end, exploitation of light emission from nanostructured Si and the improvement of the optical properties are very important.…”