Non‐Blinking Luminescence from Charged Single Graphene Quantum Dots

Abstract

Photoluminescence blinking behaviour from single quantum dots under steady illumination is an important but controversial topic. Its occurrence has impeded the use of single quantum dots in bio‐imaging. Different mechanisms have been proposed to account for it, although controversial, the most important of which is the non‐radiative Auger recombination mechanism whereby photo‐charging of quantum dots can lead to the blinking phenomenon. Here, the singly charged trion, which maintains photon emission, including the radiative recombination and non‐radiative Auger recombination, leads to fluorescence non‐blinking which was observed in photo‐charged single graphene quantum dots (GQDs). This phenomenon can be explained in terms of different energy levels in the GQDs, caused by various oxygen‐containing functional groups in the single GQDs. The suppressed blinking is due to the filling of trap sites owing to a Coulomb blockade. Our results provide a profound understanding of the special optical properties of GQDs, affording a reference for further in‐depth research.This article is protected by copyright. All rights reserved

Engineering functionalization and properties of graphene quantum dots (GQDs) with controllable synthesis for energy and display applications

“…90,109 GQDs’ π–π conjugated system is the intrinsic cause of their blue PL emission. 110,111 Therefore, the reduction, which removes functional groups like epoxide groups from the lattice of GQDs, leads to improved crystallinity and higher QY. Thirdly, avoiding aggregation of GQDs is crucial.…”

“…For instance, a recent study by Fu et al contributes to the understanding of non-blinking luminescence in single GQDs. 111 Furthermore, recent literature includes studies on the synthesis and applications of chiral GQDs, as well as investigations into the layered structures of GQDs. 240,365–367…”

A review on synthesis, properties, and biomedical applications of graphene quantum dots (GQDs)

“…Recently, Cui and Xue reported that during the oxidation of epoxy group, the ortho structure exhibited a faster non-radical decay rate compared to the meta structure [159]. Furthermore, Fu et al discussed the PL blinking phenomenon of GQDs through a non-radiative Auger recombination mechanism [160]. In another recent study, Belko et al demonstrated the potential use of GQDs' blinking in super resolution fluctuation imaging (SOFI) as controlled fluorophores [161].…”

“…Firstly, eliminating functional groups for increasing crystallinity of GQDs can enhance QY. The π-π conjugated system within GQDs is responsible for blue PL emission [160,162]. Consequently, the removal of functional groups, such as epoxy groups within the GQDs' graphene lattice through reduction processes, enhances crystallinity and QY [51,143].…”

Fast detection of Staphylococcus aureus using thiol-functionalized WS2 quantum dots and Bi2O2Se nanosheets hybrid through a fluorescence recovery mechanism

“…Hence, the wavelength-dependent emission intensity was attributed to the selective excitation and recombination of neutral excitons and defect-bound excitons at different excitation wavelengths as well as to the size distribution of QDs. 56,91 We have found the maximum intensity for an excitation wavelength of 400 nm, and hence we have used a 405 nm laser excitation for further FL measurements. The quantum yield (QY) of the synthesized WS 2 QDs was measured with 330 nm excitation at a low concentration of 1 μg mL −1 and the obtained QY was 52.1%, the highest reported to date.…”