Effect of Water Adsorption on the Photoluminescence of Silicon Quantum Dots

Abstract

The optical properties of silicon quantum dots (Si QDs) are strongly influenced by circumjacent surface-adsorbed molecules, which would highly affect their applications; however, water, as the ubiquitous environment, has not received enough attention yet. We employed the time-dependent density functional calculations to investigate the water effect of photoluminescence (PL) spectra for Si QDs. In contrast with the absorption spectra, PL spectra exhibit distinct characteristics. For Si32H38, PL presents the single maximum in the dry and humid environment, while the emission spectrum displays a dual-band fluorescence spectroscopy in the low-humidity environment. This phenomenon is also observed in the larger Si QDs. The distinct character in spectroscopy is dominated by the stretching of the Si-Si bond, which could be explained by the self-trapped exciton model. Our results shed light on the Si-water interaction that is important for the development of optical devices based on Si-coated surfaces.

Surface Dynamics and Ligand–Core Interactions of Quantum Sized Photoluminescent Gold Nanoclusters

“…For example, peptide-coated AuNCs that are solvent exposed are more sensitive to O 2 -mediated quenching 47,48, whereas AuNCs with dense, hydrophobic ligand shells are more efficient at minimizing the number of internal non-radiative relaxation pathways and collisional quenching from solvent 49,50. Other studies have also shown that the electronic (and optical) properties of quantum dot fluorophores are strongly influenced by the circumjacent surface-bound molecules 51. More detailed electronic structure investigations are required to fully understand the effects of solvent in proximity to Au 25 S 18 .…”

Si quantum dots enhancement stimulated Raman scattering of water molecules

“…Figure b is UV‐visible (VIS) absorption spectrum of Si QDs water solution; the feature peak locates at 360 nm. Due to absorption, spectrum of allylamine (amino groups)‐capped Si QDs displays a peak at 320 nm; however, the absorption spectrum of water–Si QDs shows a peak at 270 nm. This result indicates that that the surface amino groups remain on the QD surface, without being replaced by OH groups.…”

A Novel Imidazophenazine Lactam Reaction Type Recognition Cyanide Ion Fluorescence Probe

“…从图中可以看到, 当含水量从 0%增加到 10%时, S1 的荧光强度随溶液中含水量的增加而减弱. 此时水的加入使 S1 产生堆积, 但这种堆积较为无序, 因 此导致荧光减弱 [48,49] . 当含水量从 10%增加到 30%时, S1 的荧光强度随溶液中含水量的增加而增强 [50,51] .…”