Abstract
Carbon dots (C-dots) represent an emerging class of nontoxic nanoemitters that show excitation wavelength-dependent photoluminescence (PL) with high quantum yield (QY) and minimal photobleaching. The vast majority of studies focus on C-dots that exhibit the strongest PL emissions in the blue/green region of the spectrum, while longer wavelength emissions are ideal for applications such as bioimaging, photothermal and photodynamic therapy and light-emitting diodes. Effective strategies to modulate the PL emission of C-dot-based systems towards the red end of the spectrum rely on extensive conjugation of sp2 domains, heteroatom doping, solvatochromism, surface functionalization and passivation. Those approaches are systematically presented in this review, while emphasis is given on important applications of red-emissive suspensions, nanopowders and polymer nanocomposites.
Highlights
The dynamic presence of carbon dots (C-dots) in the field of nanoemitters over the last 15 years is directly related to their unique combination of three desired characteristics: inexpensive preparation, nontoxic nature and superior photophysical properties in terms of light absorption, chemiluminescence, electroluminescence, phosphorescence and upconversion [1,2,3,4,5]
GQDS are considered as a distinct subgroup of C-dots and are synthesized by various strategies including chemical vapor deposition on hexagonal boron nitride substrates [8], all-organic synthesis starting from polyphenylene dendrimers [9] and ring opening of fullerenes adsorbed to Ru metal terraces [10]
It has been recently suggested that the red/near infrared (NIR)-emissive signals recorded on C-dot based systems stem from organic-like dye molecules encapsulated within carbonaceous nanostructures and might not be related to the intrinsic properties of nanoparticles [37]
Summary
The dynamic presence of carbon dots (C-dots) in the field of nanoemitters over the last 15 years is directly related to their unique combination of three desired characteristics: inexpensive preparation, nontoxic nature and superior photophysical properties in terms of light absorption, chemiluminescence, electroluminescence, phosphorescence and upconversion [1,2,3,4,5]. A large variety of blue/green-emissive C-dots with advanced PL properties have been developed, it has been demonstrated that extensive π-conjugated domains, high levels of surface oxidation, incorporation of heteroatoms such as N, S and P and solvatochromism can give rise to red-shifted emissions [35,36]. It has been recently suggested that the red/NIR-emissive signals recorded on C-dot based systems stem from organic-like dye molecules encapsulated within carbonaceous nanostructures and might not be related to the intrinsic properties of nanoparticles [37]. This approach, might not explain the behaviour observed in GQDS and in related systems not prepared via pyrolysis. The distinct advantages of those nanomaterials in emerging applications such as bioimaging, biosensing, photothermal and photodynamic therapy, light-emitting diodes, pollutant detection and nanoforensics are highlighted
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
