Porous Silicon Bragg Reflector/Carbon Dot Hybrids: Synthesis, Nanostructure, and Optical Properties.

Naama Massad-Ivanir,Susanta Kumar Bhunia,Raz Jelinek,Ester Segal

doi:10.3389/fchem.2018.00574

Naama Massad-Ivanir, Susanta Kumar Bhunia + Show 2 more

Open Access

https://doi.org/10.3389/fchem.2018.00574

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Abstract

Carbon dots (C-dots) exhibit unique fluorescence properties, mostly depending upon their physical environments. Here we investigate the optical properties and nanostructure of Carbon dots (C-dots) which are synthesized in situ within different porous Silicon (PSi) Bragg reflectors. The resulting hybrids were characterized by photoluminescence, X-ray photoelectron, and Fourier Transform Infrared spectroscopies, as well as by confocal and transmission electron microscopy. We show that by tailoring the location of the PSi Bragg reflector photonic bandgap and its oxidation level, the C-dots emission spectral features can be tuned. Notably, their fluorescence emission can be significantly enhanced when the high reflection band of the PSi host overlaps with the confined C-dots' peak wavelength, and the PSi matrix is thermally oxidized at mild conditions. These phenomena are observed for multiple compositions of PSi Bragg reflectors/C-dots hybrids.

Highlights

In recent years, carbon dots (C-dots) have attracted considerable attention as a promising green nanomaterial for applications in sensing, bio-imaging, and optical devices owing to their unique optical properties (Lim et al, 2015; Tuerhong et al, 2017; Wang et al, 2017)
The resulting Porous silicon (PSi) layer was dissolved in an aqueous NaOH solution (0.1 M) followed by exposure to a solution composed of 1:3:1 (v/v/v) hydrofluoric acid (HF), ethanol and deionized water, respectively
Porous Silicon (PSi) Bragg reflector films with photonic bandgap centers at 425, 530, and 600 nm were fabricated by Si anodization and the detailed etching conditions are summarized in Table 1 (Materials and Methods section)

Summary

Introduction

Carbon dots (C-dots) have attracted considerable attention as a promising green nanomaterial for applications in sensing, bio-imaging, and optical devices owing to their unique optical properties (Lim et al, 2015; Tuerhong et al, 2017; Wang et al, 2017). We studied diverse types of C-dots with different emission spectra (blue, green, yellow and red) within various nanostructured Bragg reflectors with different photonic bandgap centers (425, 530, and 600 nm) and oxidation levels (freshly-etched, partially- and fully-oxidized).

Results

Conclusion