Confined-domain crosslink-enhanced emission effect in carbonized polymer dots

Tao, Songyuan; Zhou, Changjiang; Kang, Chunyuan; Zhu, Shoujun; Feng, Tanglue; Zhang, Shitong; Ding, Zhao; Zheng, Chengyu; Chen, Xia; Yang, Mingxi

doi:10.1038/s41377-022-00745-4

Cited by 68 publications

(60 citation statements)

References 51 publications

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“…As the temperature increases, more intense thermal motion and new reaction pathways become possible, resulting in further entanglement of polymer chains 36 . Owing to the shortened spatial distance, cross‐linking then proceeds in the interior of polymeric clusters, causing the structures to become more compact and stable with time 37–39 . In the cross‐linked stage, the entangled polymer chains can greatly suppress various types of nonradiative transitions (such as vibrations and rotations), thereby forcing excited electrons to return to the ground state through radiative transitions, which provides a design framework for the construction of RTP CDs.…”

Section: Introductionmentioning

confidence: 99%

Cross‐linking enhanced room‐temperature phosphorescence of carbon dots

Wang

Sun

et al. 2022

SmartMat

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Currently, there is a strong drive to discover alternative materials that exhibit room-temperature phosphorescence (RTP) for displays, bioimaging, and data security. Ideally, these materials should be nontoxic, cheap, and possess controllable photoluminescent properties. Carbon dots (CDs) possess each of these characteristics, but to date, less attention has been paid to their RTP mechanism. Herein, we synthesized a series of CDs by self-crosslinking and carbonization of precursor. The resultant CDs were luminescent and exhibited a bright, micro-second afterglow lifetime. To increase the RTP, a second microwave processing step was used to coat the CDs with polyvinyl alcohol (PVA), polyacrylamide (PAM), or tetraethyl orthosilicate (TEOS), producing CDs@PVA, CDs@PAM, and CDs@TEOS composites. The core-shell structure acted to enhance crosslinking at the surface of the CDs to boost the RTP, creating abundant energy levels for intersystem crossover. In situ X-ray photoelectron spectroscopy verified electron transfer during luminescence. Finally, we present a design rule that can be used to tune the quantum yields and RTP lifetime of CDs, based on the effective stabilization of triplet excited states through the extent and strength of cross-linking. This simple strategy provides a flexible route for guiding the further development of CDs with tailored RTP properties for various applications.

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Section: Introductionmentioning

confidence: 99%

Cross‐linking enhanced room‐temperature phosphorescence of carbon dots

Wang

Sun

et al. 2022

SmartMat

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“…Thus, new electronic transitions become accessible and the structural rigidity of the environment, hampering the energy dissipation of the absorbed photons through rotational and vibrational motions, promotes instead the radiative relaxation of the excited state originating light emission (Figure ). − This phenomenon was summarized in the concept of the cross-link-enhanced emission (CEE) effect by Yang’s group. ,− …”

Section: Ca-cd Classesmentioning

confidence: 99%

“…In fact, the CEE effect does not require specific molecules, but it is rather common when amide (or imide) cross-linkers are present, which is a characteristic of all of the CDs systems obtained from polyamine- and polycarboxylic acid-bearing precursors. For example, CDs have been prepared from citric acid with polyethyleneimine , or amino acids − or from poly(acrylic acid) with ethylenediamine. , Aromatic bis-amines have also been employed for the CD synthesis with citric acid. In particular, phenylenediamines and diaminonaphthalenes were exploited for achieving different emission colors (Table ).…”

Section: Ca-cd Classesmentioning

confidence: 99%

Citric Acid-Based Carbon Dots and Their Application in Energy Conversion

Vallan

Imahori

2022

ACS Appl. Electron. Mater.

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Carbon dot (CD) is a general term that encompasses a plethora of organic materials obtained from different reagents and different synthetic routes. Beyond this variety, carbonization has been considered for a long time as the essential process whereby completely different precursors converge into the formation of nanosized particles with resembling optical properties. In particular, CDs’ outstanding fluorescence emission is frequently attributed to the existence of large aromatic structures with extended conjugation. Nevertheless, thanks to the contribution of an increasing number of publications, nowadays the impact of these structures on the fluorescence emission has been considerably downsized. In some cases, their existence is even highly questionable. In return, in these years, more solid interpretations have been provided, according to which the chemical and emissive nature of CDs is strictly specific to the combination of synthetic precursors employed. Moreover, researchers have become more aware of the complexity of these systems, which contain not only nanoparticles but also single molecules, oligomers, and aggregates with their own fluorescent behavior. Therefore, we dedicate the first part of this review to the individual examination of different classes of citric acid-based CDs as a benchmarking CD class. A classification based on the precursors is meant to help the reader to find a common thread between the structural and optical properties of CDs. In the second part, we discuss the employment of citric acid-based CDs for energy conversion applications. This includes their exploitation as components of light-emitting diodes (LEDs), as photocatalysts for hydrogen generation and pollutant degradation, and as additives in several types of organic photovoltaic devices.

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“…The corresponding results have been reported by Qu and Lin et al, and this is significant for near-infrared emissive CNDs 15 , 16 . Crosslink-enhanced emission (CEE), a novel concept conceived by Yang and coauthors, sheds light on the emission mechanism of CNDs 17 . Cross-linking during the formation of CNDs can also increase their conjugate size to some extent, leading to a narrower bandgap of the synthesized CNDs.…”

Section: Introductionmentioning

confidence: 99%

Ultraviolet phosphorescent carbon nanodots

et al. 2022

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Phosphorescent carbon nanodots (CNDs) have generated enormous interest recently, and the CND phosphorescence is usually located in the visible region, while ultraviolet (UV) phosphorescent CNDs have not been reported thus far. Herein, the UV phosphorescence of CNDs was achieved by decreasing conjugation size and in-situ spatial confinement in a NaCNO crystal. The electron transition from the px to the sp2 orbit of the N atoms within the CNDs can generate one-unit orbital angular momentum, providing a driving force for the triplet excitons population of the CNDs. The confinement caused by the NaCNO crystal reduces the energy dissipation paths of the generated triplet excitons. By further tailoring the size of the CNDs, the phosphorescence wavelength can be tuned to 348 nm, and the room temperature lifetime of the CNDs can reach 15.8 ms. As a demonstration, the UV phosphorescent CNDs were used for inactivating gram-negative and gram-positive bacteria through the emission of their high-energy photons over a long duration, and the resulting antibacterial efficiency reached over 99.9%. This work provides a rational design strategy for UV phosphorescent CNDs and demonstrates their novel antibacterial applications.

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Confined-domain crosslink-enhanced emission effect in carbonized polymer dots

Cited by 68 publications

References 51 publications

Cross‐linking enhanced room‐temperature phosphorescence of carbon dots

Cross‐linking enhanced room‐temperature phosphorescence of carbon dots

Citric Acid-Based Carbon Dots and Their Application in Energy Conversion

Ultraviolet phosphorescent carbon nanodots

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