High efficiency photoluminescence from silicon nanocrystals prepared by plasma synthesis and organic surface passivation

Abstract

An efficient synthesis route for highly luminescent silicon quantum dots is presented. Silicon nanocrystals were synthesized in the gas phase using an argon-silane non-thermal plasma in a continuous flow reactor. Liquid phase surface passivation was used to improve the optical properties and avoid surface oxidation of the silicon quantum dots. Various alkenes, such as octadecene, dodecene and styrene, were covalently bonded to the plasma-produced particles, while strictly avoiding exposure of the raw powder to oxidizing agents. Stable colloidal solutions of silicon quantum dots with ensemble quantum yields between 60% and 70% were achieved.

Plasma‐Assisted Synthesis of Silicon Nanocrystal Inks

“…First experiments used 1-dodecene, which when grafted to silicon crystals using liquid-phase hydrosilylation had enabled us to achieve stable silicon nanocrystal colloids with high photoluminescence quantum yields of > 60 %. [15][16][17] Figure 1a demonstrates the effectiveness of the in-flight plasma grafting in preparing silicon inks. The vial on the left shows a solution prepared from nanocrystals that were subjected to plasma-grafting of 1-dodecene.…”

“…Examples include silicon colloids for which nanocrystals were produced in the gas-phase through laser pyrolysis, [13,14] or non-thermal plasma synthesis. [15][16][17] Unfortunately, performing the surface functionalization as the second step in the liquid phase introduces disadvantages such as long reaction times, and the need to transfer materials after the synthesis into different surface treatment reactors. This transfer step often needs to be performed under exclusion of oxygen, increasing the complexcity of the process.…”

Using CdTe/ZnSe core/shell quantum dots to detect DNA and damage to DNA

“…Different types of core/shell QDs (CdSe/ZnS, CdTe/ZnS, and CdTe/ ZnSe), core/shell/shell QDs (CdTe/CdS/ZnS and CdSe/ CdTe/ZnSe), and environmentally friendly QDs (CuInSe, Ag 2 S, and Si) have been synthesized for various purposes. [19][20][21][22][23][24][25][26][27][28] In our previous study, we reported that CdTe/ZnSe core/shell QDs can be applied for in vitro imaging of chicken tissue and embryo. 29 The biological applications of QDs can be hampered by their inherently low solubility in water.…”

Biodegradable Luminescent Silicon Quantum Dots for Two Photon Imaging Applications

“…7 The need for inherently non-toxic components for quantum dots has partially motivated the development of silicon quantum dots (SiQDs). [8][9][10][11][12] However, despite recent progress in development of SiQDs for bioimaging, further advances are required, including development of optimal encapsulation strategies, increasing its quantum yield, and creating nanoconstructs that exploit its biodegradability. Additionally, physiological factors affecting the performance and degradation of silicon nanoparticles are not yet well understood.…”