Optical processes in carbon nanocolloids

Ragazzon, Giulio; Cadranel, Alejandro; Ushakova, Elena V.; Wang, Yichun; Guldi, Dirk M.; Rogach, Andrey L.; Kotov, Nicholas A.; Prato, Maurizio

doi:10.1016/j.chempr.2020.11.012

Cited by 91 publications

(99 citation statements)

References 97 publications

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“…The PL emission of CPDs in the visible and near-infrared regions can be effectively tuned. The complex optical properties of CPDs have been summarized in a few review papers published recently 20,21,45 . It has been reported that the emission originates from four types of PL centers (molecular-state, crosslink-enhanced-emission (CEE)-effect-related state, sp 2 subdomains (carbon core state), and surface state) 45 .…”

Section: Precursor-dependent Emissionmentioning

confidence: 99%

“…The structural features vary within a sample set. Therefore, CPD is better identified as a material and not a precise molecular or nanoscale entity 21 . This is also one of the reasons why most CPD materials exhibit excitationdependent PL properties.…”

Section: Nomenclature Of Cpdsmentioning

confidence: 99%

“…In recent years, researchers have attempted the chemical synthesis of CDs starting from molecules or polymer precursors (bottom-up routes) to gain better control of the final materials 21 . The precursors generally bear polymerizable moieties such as hydroxyl groups (−OH), carboxyl groups (−COOH), amino groups (−NH 2 ), and double bonds (−C=C) in their skeleton that can participate in condensation/addition-polymerization reactions.…”

Section: Introductionmentioning

confidence: 99%

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Precursor-dependent structural diversity in luminescent carbonized polymer dots (CPDs): the nomenclature

et al. 2021

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Carbon dots (CDs) have received immense attention in the last decade because they are easy-to-prepare, nontoxic, and tailorable carbon-based fluorescent nanomaterials. CDs can be categorized into three subgroups based on their morphology and chemical structure: graphene quantum dots (GQDs), carbon quantum dots (CQDs), and carbonized polymer dots (CPDs). The detailed structures of the materials can vary significantly, even within the same category. This property is particularly predominant in chemically synthesized CPDs, as their formation proceeds via the polymerization–carbonization of molecules or polymer precursors. Abundant precursors endow CPDs with versatile structures and properties. A wide variety of carbon nanomaterials can be grouped under the category of CPDs because of their observed diversity. It is important to understand the precursor-dependent structural diversity observed in CPDs. Appropriate nomenclature for all classes and types of CPDs is proposed for the better utilization of these emerging materials.

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Section: Precursor-dependent Emissionmentioning

confidence: 99%

Section: Nomenclature Of Cpdsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Precursor-dependent structural diversity in luminescent carbonized polymer dots (CPDs): the nomenclature

et al. 2021

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“…Their emission peak was at 405 nm, and their chirality could be regulated by adjusting the reaction time. However, despite such encouraging progress, there are few reports regarding, for example, the challenging preparation of red‐emitting and wavelength‐tunable Ch‐CPDs [2a, 9] . Three factors are key for the synthesis of red‐emitting CPDs: (1) precursors, (2) reaction temperature, and (3) reaction solvents [10] .…”

Section: Introductionmentioning

confidence: 99%

Rational Design of Multicolor‐Emitting Chiral Carbonized Polymer Dots for Full‐Color and White Circularly Polarized Luminescence

et al. 2021

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Light-emitting chiral carbonized polymer dots (Ch-CPDs) are attracting great interest because of their extraordinary photonic properties,b ut modulating their band-gap emission, especially at long wavelength, and maintaining their chiral structure to achieve multicolor,high-emission Ch-CPDs remains challenging.R eported here for the first time is the synthesis of red-and multicolor-emitting Ch-CPDs using the common precursors l-/d-tryptophan and o-phenylenediamine, and asolvothermal approach at one temperature.The quantum yield of the Ch-CPDs was between 31 %a nd 54 %. Supramolecular self-assembly provided multicolor-emitting Ch-CPDs showing novel circularly polarized luminescence,w ith the highest dissymmetric factor (g lum )o f1 10 À2 .I mportantly, circularly polarized white-emitting CPDs were fabricated for the first time by tuning the mixing ratio of the three colored Ch-CPDs in agel. This strategy affords exciting opportunities for designing functional chiroptical materials.

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“…Such a comparability in nanoscale configuration illustrated in Figure 1 must be the assumption implicitly or explicitly behind the popular "one-pot" carbonization approach for the synthesis of samples that exhibit some of the characteristic properties of CDots, such as the bright and colorful fluorescence emissions. [1,[22][23][24] While convenient, the thermal carbonization synthesis is understandably difficult to control, generally yielding complicated mixtures at both the sample and sample structure levels. In fact, the "dot" samples from the thermal carbonization synthesis should be considered more appropriately as carbon/organic hybrids that are randomly structured at the nanoscale, dubbed "nano-hybrids" (Figure 1).…”

Section: Carbon Dotmentioning

confidence: 99%

Chemical Reactions in Thermal Carbonization Processing of Citric Acid-Urea Mixtures

Liang¹,

Wang²,

Yang³

et al. 2021

General Chemistry

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Carbon dots are small carbon nanoparticles with effective surface passivation by mostly organic species. For such a simple and well-defined nanoscale structure, the classical and most reliable synthesis is the use of pre-existing small carbon nanoparticles for surface chemical functionalization with organic molecules. However, a more popular synthetic approach in the literature has been the "one-pot" carbonization of organic precursors, which with appropriate processing conditions could in principle create local structures in the resulting dot-like entities that may be comparable to the structural configuration in carbon dots, though the carbonization can also easily produce colored organic materials crosslinked into the sample structures. An extreme example was the thermal processing of the specific organic precursor mixtures including only citric acid with formamide or urea to yield samples of red/near-IR absorption and emission features, which prompted the claims of "red/near-IR carbon dots". In reality, these spectral features have nothing to do with nanoscale carbon, let alone carbon dots, but simply associated with molecular dyes/chromophores produced in chemical reactions of the specific precursor mixtures under the thermal processing conditions intended for carbonization. In this work, the isolation and identification of the responsible molecular dyes/chromophores were pursued. The results present further evidence for the conclusion that the red/near-IR absorption and emission features have nothing to do with carbon dots.

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Optical processes in carbon nanocolloids

Cited by 91 publications

References 97 publications

Precursor-dependent structural diversity in luminescent carbonized polymer dots (CPDs): the nomenclature

Precursor-dependent structural diversity in luminescent carbonized polymer dots (CPDs): the nomenclature

Rational Design of Multicolor‐Emitting Chiral Carbonized Polymer Dots for Full‐Color and White Circularly Polarized Luminescence

Chemical Reactions in Thermal Carbonization Processing of Citric Acid-Urea Mixtures

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