Microplasma‐Induce Liquid Chemistry for Stabilizing of Silicon Nanocrystals Optical Properties in Water

Abstract

In this report, we demonstrate stabilization of photoluminescence (PL) properties of environmentally and biologically friendly silicon nanocrystals (SiNCs) in water through atmospheric pressure radio‐frequency (RF) microplasma processing at room temperature. The PL of the SiNCs is enhanced after microplasma processing, which involves three‐dimensional engineering of SiNCs directly in water avoiding degradation by surface functionalization. Moreover, we compare the RF microplasma process with direct‐current microplasma processing, whereby the two approaches lead to very similar SiNCs optical properties and surface characteristics. The induced unique chemistry and SiNCs stability in water have wide implications for the SiNCs processability and applications in energy devices, biology and medicine.

Temperature-dependent photoluminescence of surface-engineered silicon nanocrystals

“…SiNCs are prepared by electrochemical etching where a silicon wafer (p–type boron doped, 0.1 Ω cm, thickness 0.5 mm) was used12. SiNCs were collected as powder by subsequent mechanical pulverization.…”

“…1c shows the symmetries that correspond to the different crystalline planes of the particle under analysis, further confirming its crystalline character. In addition chemical composition and surface characteristics have been extensively studied in our previous reports which included X–ray photoelectron spectroscopy (XPS)13 and Fourier transform spectroscopy (FTIR)48121415.…”

Enhancement of polymer solar cell performance under low-concentrated sunlight by 3D surface-engineered silicon nanocrystals

“…The RF microplasma was generated within a quartz capillary between two ring-electrodes and a third ringelectrode was used for plasma ignition via a high voltage pulse [12]. Because the microplasma was generated close to the end of the quartz capillary, a small plasma jet (~mm) could be formed outside the capillary.…”

“…Pure helium gas was flown inside the quartz capillary at the rate of 250 sccm. The applied power was kept at 60 W @450 MHz [12]. The distance between the end of the quartz capillary and the surface of liquid dispersion was adjusted around 2 mm.…”

“…In order to induce 3D surface engineering of surfactantfree Si-ncs an RF microplasma at atmospheric pressure has been used [11,12]. The as-prepared Si-ncs powder was then dispersed in ethanol (2.5 mg Si-ncs powder was wetted in 5 ml of ethanol) and the microplasma treatment was applied to engineer the Si-ncs surface.…”