Room temperature phosphorescence from moisture-resistant and oxygen-barred carbon dot aggregates

Chen, Yonghao; He, Jiangling; Hu, Chaofan; Zhang, Haoran; Lei, Bingfu; Liu, Yingliang

doi:10.1039/c7tc01615h

Cited by 99 publications

(95 citation statements)

References 38 publications

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“…Some CD‐based RTP materials have already been reported. However, the typical methods for obtaining these RTP materials involves embedding CDs into a polymer matrix (e.g., poly(vinyl alcohol), polyurethane, and silica gel), layered double hydroxides, host matrices, two‐component matrices, or similar systems. These matrices are crucial for stabilizing phosphors with regards to the long lifetime triplet state, which can be easily quenched by molecular vibrations, oxygen molecules, and high temperatures .…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, suppressing the quenching of triplet excitons which originate from CN/CN relevant moieties in CDs is an effective way to achieve self‐protective RTP. It is well‐documented that hydrogen bonding can effectively lock emissive species and restrain their intramolecular motions . The introduction of fluorine atoms is a promising technique for improving hydrogen bonding interactions, which may provide steric protection around the phosphor and effectively enhance the stability of RTP emissions .…”

Section: Introductionmentioning

confidence: 99%

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Self‐Protective Room‐Temperature Phosphorescence of Fluorine and Nitrogen Codoped Carbon Dots

Peng

Feng

Chen

et al. 2018

Adv Funct Materials

323

218

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The unstable triplet excited state is a core problem when developing selfprotective room temperature phosphorescence (RTP) in carbon dots (CDs). Here, fluorine and nitrogen codoped carbon dots (FNCDs) with long-lived triplet excited states, emitting pH-stabilized blue fluorescence and pHresponsive green self-protective RTP, are reported for the first time. The self-protective RTP of FNCDs arises from n-π * electron transitions for CN/CN bonds with a small energy gap between singlet and triplet states at room temperature. Moreover, the interdot/intradot hydrogen bonds and steric protection of CF bonds reduce quenching of RTP by oxygen at room temperature. The RTP emission of FNCDs shows outstanding reversibility, while the blue fluorescence emission has good pH stability. Based on these FNCDs, a data encoding/reading strategy for advanced anticounterfeiting is proposed via time-resolved luminescence imaging techniques, as well as steganography of complex patterns.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Self‐Protective Room‐Temperature Phosphorescence of Fluorine and Nitrogen Codoped Carbon Dots

Peng

Feng

Chen

et al. 2018

Adv Funct Materials

323

218

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“…Since then, RTP materials have been developed from CDs dispersed into polyurethane,13 silica gel,14 polymer composite matrix (urea and biuret),15 KAl(SO 4 ) 2 · x H 2 O,16 and NaCl hybrid crystals,17 which were mainly applied in the field of document security. Recently, Liu et al18 and Lin et al19 designed a matrix‐free RTP of NCDs. The synthesized CDs act as both a solidified host and a luminescent object in a solid‐state without introducing an additional support matrix.…”

Section: Introductionmentioning

confidence: 99%

Visible‐Light‐Excited Ultralong‐Lifetime Room Temperature Phosphorescence Based on Nitrogen‐Doped Carbon Dots for Double Anticounterfeiting

Gao

Zhang

Shuang

et al. 2020

Advanced Optical Materials

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of RTP materials with excellent properties is always a challenge, and this can be attributed to the spin-forbidden nature of triplet exciton transitions. Till now, RTP materials mainly include metal complexes and pure organic compounds, [6] which have several disadvantages such as high cost, high toxicity, and complicated preparation process. Also, the commonly reported RTP materials can be excited only under ultraviolet light, and their excitation spectrum under the ultraviolet region is not convenient for certain applications. Contrary to ultraviolet light, visible light is safer to use and can penetrate deeper into biological analysis and imaging; hence easily used in practical applications. Besides, visible light is more superior than ultraviolet light and has received widespread applications. [7] Thus, enormous efforts have been devoted to discovering novel RTP materials that can be excited by visible light. Currently, only a few visible-light-induced phosphorescent materials [8] have been implemented.As one of the most popular nanomaterials, carbon dots (CDs) have attracted much interest because of their low toxicity, excellent optical performance, high light stability, and environmental friendliness. [9] They are widely applied in biological imaging, [10] securing documents, [11] and in light-emitting devices. [3] Moreover, CDs are effective optical URTP materials which makes them very attractive in anticounterfeiting. Zhao and co-workers [12] pioneered the RTP of CDs by introducing a polymer poly(vinyl alcohol) as a protective matrix, and the CDs were used successfully for securing documents. Since then, RTP materials have been developed from CDs dispersed into polyurethane, [13] silica gel, [14] polymer composite matrix (urea and biuret), [15] KAl(SO 4 ) 2 ·xH 2 O, [16] and NaCl hybrid crystals, [17] which were mainly applied in the field of document security. Recently, Liu et al. [18] and Lin et al. [19] designed a matrix-free RTP of NCDs. The synthesized CDs act as both a solidified host and a luminescent object in a solid-state without introducing an additional support matrix. Also, Dong et al. constructed a novel, matrix-free NCDs based on a one-step high-temperature polymerization method that binds a polyaspartic acid chain to the NCDs surface, and further designed it for safe inks. [20] These construction strategies overcame the complicated synthesis process of screening dispersion media and extended the utilization Visible light is ubiquitous and safer than ultraviolet light; however, synthesizing ultralong-lifetime room temperature phosphorescent (URTP) carbon dots (CDs) with visible-light excitation remains a formidable challenge. Herein, an easy and fast method for synthesizing visiblelight-excited URTP CDs is devised. The synthesized CDs have URTP lifetime of 1.51 s which is a relatively long life RTP lifetime ever reported. Furthermore, it is revealed that the dense core of CDs, the formation of long-chain polymers on the surface, and the presence of hydrogen bond skeleton play a crucial ...

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“…[15,19,34] According to these considerations,w ehave found ao nepot method for the facile and quick preparation of ultralong RTP( URTP) CDs.A ss hown in Figure 1a,b,g ram-scale URTP CDs can be obtained in afew minutes via microwaveassisted heating of an ethanolamine and phosphoric acid aqueous solution, and subsequent dialysis purification and freeze-drying (more details in Supporting Information). [26][27][28][29][30][31][32] Note that the as-developed method features facile,quick and scalable merits,t he obtained product possesses URTP life-time and could potentially be employed as security ink in anti-counterfeiting and information protection. Importantly,t he CDs present the longest RTPlifetime to be 1.46 s(more than 10 s to naked eye,F igure 1c and Video 1i nS upporting Information) among the reported CDs-based materials to date.…”

mentioning

confidence: 99%

Facile, Quick, and Gram‐Scale Synthesis of Ultralong‐Lifetime Room‐Temperature‐Phosphorescent Carbon Dots by Microwave Irradiation

et al. 2018

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Long-lifetime room-temperature phosphorescence (RTP) materials are important for many applications, but they are highly challenging materials owing to the spin-forbidden nature of triplet exciton transitions. Herein, a facile, quick and gram-scale method for the preparation of ultralong RTP (URTP) carbon dots (CDs) was developed via microwave-assisted heating of ethanolamine and phosphoric acid aqueous solution. The CDs exhibit the longest RTP lifetime, 1.46 s (more than 10 s to naked eye) for CDs-based materials to date. The doping of N and P elements is critical for the URTP which is considered to be favored by a n→π* transition facilitating intersystem crossing (ISC) for effectively populating triplet excitons. In addition, possibilities of formation of hydrogen bonds in the interior of the CDs may also play a significant role in producing RTP. Potential applications of the URTP CDs in the fields of anti-counterfeiting and information protection are proposed and demonstrated.

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Room temperature phosphorescence from moisture-resistant and oxygen-barred carbon dot aggregates

Abstract: Aggregation-induced room temperature phosphorescence of carbon dots was first found and the relevant mechanism was investigated.

Cited by 99 publications

References 38 publications

Self‐Protective Room‐Temperature Phosphorescence of Fluorine and Nitrogen Codoped Carbon Dots

Self‐Protective Room‐Temperature Phosphorescence of Fluorine and Nitrogen Codoped Carbon Dots

Visible‐Light‐Excited Ultralong‐Lifetime Room Temperature Phosphorescence Based on Nitrogen‐Doped Carbon Dots for Double Anticounterfeiting

Facile, Quick, and Gram‐Scale Synthesis of Ultralong‐Lifetime Room‐Temperature‐Phosphorescent Carbon Dots by Microwave Irradiation

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