Deep Ultraviolet Photoluminescence of Water-Soluble Self-Passivated Graphene Quantum Dots

Abstract

Glucose-derived water-soluble crystalline graphene quantum dots (GQDs) with an average diameter as small as 1.65 nm (∼5 layers) were prepared by a facile microwave-assisted hydrothermal method. The GQDs exhibits deep ultraviolet (DUV) emission of 4.1 eV, which is the shortest emission wavelength among all the solution-based QDs. The GQDs exhibit typical excitation wavelength-dependent properties as expected in carbon-based quantum dots. However, the emission wavelength is independent of the size of the GQDs. The unique optical properties of the GQDs are attributed to the self-passivated layer on the surface of the GQDs as revealed by electron energy loss spectroscopy. The photoluminescence quantum yields of the GQDs were determined to be 7-11%. The GQDs are capable of converting blue light into white light when the GQDs are coated onto a blue light emitting diode.

Biocompatibility and toxicity of graphene quantum dots for potential application in photodynamic therapy

“…The functional groups (O-H, C-H, and C=C) located at the surface of the GQDs act as a passivation layer. This self-passivated surface layer facilitates the water solubility of GQDs [35,36] . The maximum luminescence peak was centered at around 460 nm (from 370 -700 nm) at an excitation wavelength of 360 nm as previously reported by us [28] with quantum yield of 7.12% (Supplementary Table 1 and …”

Sensitivity to Heavy-Metal Ions of Unfolded Fullerene Quantum Dots

“…The physical origin of the photoluminescence (PL) from these carbonbased nanoparticles is still quite controversial and different mechanisms have been suggested, possibly acting together, mainly based on quantum confinement in sp 2 domains with a strong influence from edge and oxygen-containing functional groups [14][15][16][17][18]. Nonetheless, several groups have reported a characteristic fluorescence with uniform and stable features in aqueous solution of GOQDs prepared by a variety of methods, either based on bottom-up or on top-down synthesis from graphite [19][20][21][22][23][24][25][26][27]. The spectral profile and peak-emission wavelength of this emission can relatively be controlled by tailoring dimensions, chemical functionalization and excitation wavelength.…”

Efficiency Enhancement of Silicon Heterojunction Solar Cells via Photon Management Using Graphene Quantum Dot as Downconverters

“…Graphene quantum dots (GQDs), exhibiting unique semiconducting properties, 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 5 have becoming a newly emerged material for optoelectronic applications. 11,12 The bandgap of GQDs can be tuned by adjusting their chemical functional groups. 12 Additionally, the most intriguing feature of GQDs for optical applications is the photon downconversion property, which enables them to absorb photons in shorter wavelength regions and then emit photons in longer wavelength regions.…”