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Journal ArticleDOI: 10.1021/ACSSUSCHEMENG.0C09133

Color Emission Carbon Dots with Quench-ResixAstant Solid-State Fluorescence for Light-Emitting Diodes

04 Mar 2021-ACS Sustainable Chemistry & Engineering (American Chemical Society)-Vol. 9, Iss: 10, pp 3901-3908
Abstract: Since carbon dots (CDs) were reported in 2004, they have been widely used in various fields due to their outstanding optical properties. However, most CDs are self-quenched due to the direct π–π in...

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Topics: Carbon (53%)

9 results found

Journal ArticleDOI: 10.1002/ANIE.202103361
Ting Meng1, Zifei Wang1, Ting Yuan1, Xiaohong Li1  +3 moreInstitutions (1)
19 Jul 2021-Angewandte Chemie
Abstract: The negative impact of rare-earth elements (REEs) on the environment, limited supply and high cost prompt the need for REE-free phosphor-converted white light-emitting diodes (LEDs). Here, we report the gram-scale synthesis of red/green/blue solid-state bandgap fluorescent carbon quantum rings (R/G/B-SBF-CQRs) with high quantum yields up to 30-46 %. This was achieved using cyano-group-bearing p-phenyldiacetonitrile as precursor and forming carbon quantum rings of different diameters through the linkage of curved carbon quantum ribbons of different lengths. The results show the role of cyano groups in inducing the curvature of the carbon quantum ribbons for CQR formation and emission of stable solid-state bandgap fluorescence. R/G/B-SBF-CQRs-phosphor-based LEDs emitted warm white light with low CCT (3576 K), high CRI (96.6), and high luminous efficiency (48.7 lm W-1 ), comparable to REE-phosphor-based LEDs.

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Topics: Quantum dot (53%), Light-emitting diode (52%)

4 Citations

Open access
15 Apr 2017-
Abstract: Multicolor bandgap fluorescent carbon quantum dots (MCBF-CQDs) from blue to red with quantum yield up to 75% are synthesized using a solvothermal method. For the first time, monochrome electroluminescent light-emitting diodes (LEDs) with MCBF-CQDs directly as an active emission layer are fabricated. The maximum luminance of blue LEDs reaches 136 cd m-2 , which is the best performance for CQD-based monochrome electroluminescent LEDs.

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2 Citations

Journal ArticleDOI: 10.1016/J.CARBON.2021.10.002
Chuang He1, Peng Xu1, Xuanhan Zhang1, Wu-Jian Long1Institutions (1)
01 Jan 2022-Carbon
Abstract: Carbon dots (CDs), a rising star in carbon nanomaterials, have attracted enormous attention since their discovery in 2004. Up to now, a large number of approaches have been developed to synthesize CDs, and many efforts have been made to exploit facile, low-cost and large-scale preparation routes. At the same time, photoluminescence (PL) mechanisms of CDs have been tremendously investigated, primarily attributed to surface state, carbon core state, molecule state and their synergistic effect. And on account of their favorable properties, such as excellent optical properties, outstanding biocompatibility, attractive catalytic performance, ultrasmall size, low toxicity and environmental friendliness, CDs have been extensively employed in biomedicine, sensing, catalysis, optoelectronic devices, lubrication, etc. This review comprehensively summarizes the development of synthetic strategies, PL mechanisms and promising applications of CDs. Based on the summary, the prospects and challenges for research into CDs are discussed in depth. This review aims to encourage related researchers to overcome various existing technical challenges, make up the insufficiency of the existing research and tap into the full potential of CDs.

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1 Citations

Open accessJournal ArticleDOI: 10.1016/J.COLSURFA.2021.128023
Abstract: A blue fluorescent Si/CDs is successfully synthesized via a conventional solvothermal method, which can serve as a sensitive fluorescent sensor to detect Hg2+ ions in water. The synthesized Si/CDs material exhibits excellent optical properties, high chemical and structural stability in an aqueous solution. Under natural light, the mixture is a colorless suspension while under ultraviolet light, it can emit bright blue fluorescence and the maximum excitation and emission wavelengths are 377 and 464 nm, respectively. Particularly, Hg2+ can lead to nearly complete fluorescence quenching of the material suspension and the emission intensity of the constructed fluorescent sensing system linearly decreases with increasing Hg2+ concentration in the range of 0 - 200 μM with a detection limit of 26.7 nM (S/N = 3). The proposed method has been successfully applied in detection of Hg2+ content in environmental and drinking water samples. In addition, the test paper strips based on fluorescent Si/CDs are also prepared by an immersion method for rapid and quantitative detection of Hg2+ in water environment through a visual mode.

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Topics: Water environment (58%), Ultraviolet light (55%), Fluorescence (55%) ... read more

Journal ArticleDOI: 10.1088/1361-6528/AC2F25
15 Jan 2022-Nanotechnology
Abstract: Fluorescent carbon dots (CDs) have attracted considerable interest due to their superior optical properties and facile preparation. In this work, O-phenylenediamine and melamine were used as precursors for the one-step hydrothermal synthesis of novel orange emissive CDs (O-CDs) in an aqueous solution. The fluorescence intensity (580 nm) of the O-CDs exhibited a good linear relationship with Ag+in the range of 0.0-50.0μM with the detection limit of 0.289μM. Moreover, the O-CDs were successfully used to determine Ag+in biological samples (Hela cells) because of their low cytotoxicity, and good biocompatibility. Besides, the O-CDs-doped solid-phase detection materials (test paper and hydrogel) were employed to monitor Ag+qualitatively and quantitatively, indicated that the O-CDs had a great capacity for the detection of Ag+in biological and environmental areas. Based on their extraordinary fluorescence property, the O-CDs could also be used as security ink. Overall, based on their excellent fluorescent performance, the CDs in this study have significant potential for practical application toward solid-phase sensing and security ink.

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43 results found

Open accessJournal ArticleDOI: 10.1002/ADMA.201704740
Xiang Miao1, Xiang Miao2, Dan Qu1, Dongxue Yang1  +4 moreInstitutions (3)
01 Jan 2018-Advanced Materials
Abstract: Multiple-color-emissive carbon dots (CDots) have potential applications in various fields such as bioimaging, light-emitting devices, and photocatalysis. The majority of the current CDots to date exhibit excitation-wavelength-dependent emissions with their maximum emission limited at the blue-light region. Here, a synthesis of multiple-color-emission CDots by controlled graphitization and surface function is reported. The CDots are synthesized through controlled thermal pyrolysis of citric acid and urea. By regulating the thermal-pyrolysis temperature and ratio of reactants, the maximum emission of the resulting CDots gradually shifts from blue to red light, covering the entire light spectrum. Specifically, the emission position of the CDots can be tuned from 430 to 630 nm through controlling the extent of graphitization and the amount of surface functional groups, COOH. The relative photoluminescence quantum yields of the CDots with blue, green, and red emission reach up to 52.6%, 35.1%, and 12.9%, respectively. Furthermore, it is demonstrated that the CDots can be uniformly dispersed into epoxy resins and be fabricated as transparent CDots/epoxy composites for multiple-color- and white-light-emitting devices. This research opens a door for developing low-cost CDots as alternative phosphors for light-emitting devices.

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535 Citations

Journal ArticleDOI: 10.1002/ANIE.201411004
02 Mar 2015-Angewandte Chemie
Abstract: Although reports have shown shifts in carbon dot emission wavelengths resulting from varying the excitation wavelength, this excitation-dependent emission does not constitute true tuning, as the shifted peaks have much weaker intensity than their dominant emission, and this is often undesired in real world applications. We report for the first time the synthesis and photoluminescence properties of carbon dots whose peak fluorescence emission wavelengths are tunable across the entire visible spectrum by simple adjustment of the reagents and synthesis conditions, and these carbon dots are excited by white light. Detailed material characterization has revealed that this tunable emission results from changes in the carbon dots' chemical composition, dictated by dehydrogenation reactions occurring during carbonization. These significantly alter the nucleation and growth process, resulting in dots with either more oxygen-containing or nitrogen-containing groups that ultimately determine their photoluminescence properties, which is in stark contrast to previous observations of carbon dot excitation-dependent fluorescence. This new ability to synthesize broadband excitable carbon dots with tunable peak emissions opens up many new possibilities, particularly in multimodal sensing, in which multiple analytes and processes could be monitored simultaneously by associating a particular carbon dot emission wavelength to a specific chemical process without the need for tuning the excitation source.

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Topics: Photoluminescence (54%), Visible spectrum (51%), Carbon (51%)

443 Citations

Journal ArticleDOI: 10.1002/ADMA.201604436
Fanglong Yuan1, Zhibin Wang2, Xiaohong Li1, Yunchao Li1  +3 moreInstitutions (3)
01 Jan 2017-Advanced Materials
Abstract: Multicolor bandgap fluorescent carbon quantum dots (MCBF-CQDs) from blue to red with quantum yield up to 75% are synthesized using a solvothermal method. For the first time, monochrome electroluminescent light-emitting diodes (LEDs) with MCBF-CQDs directly as an active emission layer are fabricated. The maximum luminance of blue LEDs reaches 136 cd m-2 , which is the best performance for CQD-based monochrome electroluminescent LEDs.

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417 Citations

Journal ArticleDOI: 10.1002/ADMA.201702910
Zifei Wang1, Fanglong Yuan1, Xiaohong Li1, Yunchao Li1  +3 moreInstitutions (3)
01 Oct 2017-Advanced Materials
Abstract: Red emissive carbon quantum dots (R-CQDs) with quantum yield of 53% is successfully prepared. An ultraviolet (UV)-pumped CQD phosphors-based warm white light-emitting diode (WLED) is realized for the first time and achieves a color rendering index of 97. This work provides a new avenue for the exploration of low cost, environment-friendly, and high-performance CQD phosphors-based warm WLEDs.

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Topics: Color rendering index (52%)

400 Citations

Journal ArticleDOI: 10.1002/ADMA.201503380
Yonghao Chen1, Mingtao Zheng1, Yong Xiao1, Hanwu Dong1  +5 moreInstitutions (1)
01 Jan 2016-Advanced Materials
Abstract: Self-quenching in the aggregation state is overcome, and tunable solid-state photoluminescence of carbon-dot powder is achieved. Furthermore, based on the controllable optical property in organic solvents, a novel concept, i.e., constructing dual-fluorescence morphologies from single luminescent species, is presented to realize white-light emission.

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367 Citations