Fluorescent Carbon Dots: Fantastic Electroluminescent Materials for Light‐Emitting Diodes

Zhao, Biao; Tan, Zhan’ao

doi:10.1002/advs.202001977

Cited by 192 publications

(120 citation statements)

References 146 publications

(185 reference statements)

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“…In some cases, CDs can experience so called afterglow emission, with long PL lifetimes on the time scale of milliseconds or even seconds. The afterglow of CDs originates from their excited triplet state related emission, [113][114][115][116] where the lowest excited state is depopulated via intersystem crossing (ISC) to triplet state (T 1 ), which is then followed by radiative emission (phosphorescence, Phos. ); alternatively, delayed fluorescence (DF) process is also possible as shown in Figure 5a.…”

Section: Time-resolved Photoluminescencementioning

confidence: 99%

Optical Properties of Carbon Dots in the Deep‐Red to Near‐Infrared Region Are Attractive for Biomedical Applications

Ushakova

Rogach

et al. 2021

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range (NIR-I region: 700-900 nm; NIR-II region: 1000-1700 nm). [15][16][17][18][19][20] Deep tissue penetration can be realized in this spectral range owing to the low degree level of photon absorption, scattering, and autofluorescence from tissues. [21,22] Therefore, imaging and therapeutic agents which operate in the DR to NIR region are highly desired. For CDs, strong PL in the blue and green region has been reported on numerous occasions, with PL quantum yields (QY) up to 90%, [23,24] while CDs with efficient longer wavelength emission have experienced extensive development only recently. Starting from the first report on the orange emissive CDs (PL peak at 580 nm) with a PL QY of 46%, [25] red emissive CDs with PL peak at 628 nm and PL QY of 53%, [26] and NIR emissive CDs with PL peak at 715 nm and PL QY of 43% [27] were introduced. A number of strategies, such as enlarging the π-conjugated structure, enhancing the surface oxidation, and employing proper precursors such as phenylenediamines were proved as effective for realization of such CDs. This review starts from summary of synthetic strategies toward CDs with absorption/PL at the wavelength from 650 nm and into the NIR-I and NIR-II spectral region. We then consider in detail the Stokes and anti-Stokes PL (ASPL), chemiluminescence (CL) and formation of reactive oxygen species (ROS) for the DR/NIR CDs. At the end, we provide a concise summary of already reported biomedical applications of CDs, such as in the photoacoustic (PA) imaging and photothermal therapy (PTT), photodynamic therapy (PDT), and their use as bioimaging agents and drug carriers.Carbon dots (CDs) represent a recently emerged class of luminescent materials with a great potential for biomedical theranostics, and there are a lot of efforts to shift their absorption and emission toward deep-red (DR) to near-infrared (NIR) region falling in the biological transparency window. This review offers comprehensive insights into the synthesis strategies aimed to achieve this goal, and the current approaches of modulating the optical properties of CDs over the DR to NIR region. The underlying mechanisms of their absorption, photoluminescence, and chemiluminescence, as well as the related photophysical processes of photothermal conversion and formation of reactive oxygen species are considered. The already available biomedical applications of CDs, such as in the photoacoustic imaging and photothermal therapy, photodynamic therapy, and their use as bioimaging agents and drug carriers are then shortly summarized.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/smll.202102325. Figure 12. a) In vivo NIR fluorescence images of a mouse stomach before (left) and after (right) gavage injection of CDs in PVP aqueous solution.Reproduced with permission. [46] Copyright 2018, Wiley-VCH. b) NIR fluorescence images of mouse tumor after intravenous injection of CDs at various time points. c) NIR fluorescence of H22 tumors that were dissected from mice at ...

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Section: Time-resolved Photoluminescencementioning

confidence: 99%

Optical Properties of Carbon Dots in the Deep‐Red to Near‐Infrared Region Are Attractive for Biomedical Applications

Ushakova

Rogach

et al. 2021

Small

112

101

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“…Light‐emitting diodes (LEDs) represent devices that can enable photon emission by driving electrons and holes to recombine with the assist of an external electric field. [ 312 , 313 ] Due to the favorable bandgap, outstanding electrostatic tunability and excellent mechanical properties, 2DLMs have demonstrated grand potential in LEDs as well. [ 314 , 315 , 316 ] Nevertheless, there are still several issues to be addressed prior to the extensive utilization of 2DLMs in LED.…”

Section: Discussionmentioning

confidence: 99%

2D Layered Material Alloys: Synthesis and Application in Electronic and Optoelectronic Devices

Yao

Yang

2021

Advanced Science

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2D layered materials (2DLMs) have come under the limelight of scientific and engineering research and broke new ground across a broad range of disciplines in the past decade. Nevertheless, the members of stoichiometric 2DLMs are relatively limited. This renders them incompetent to fulfill the multitudinous scenarios across the breadth of electronic and optoelectronic applications since the characteristics exhibited by a specific material are relatively monotonous and limited. Inspiringly, alloying of 2DLMs can markedly broaden the 2D family through composition modulation and it has ushered a whole new research domain: 2DLM alloy nano-electronics and nano-optoelectronics. This review begins with a comprehensive survey on synthetic technologies for the production of 2DLM alloys, which include chemical vapor transport, chemical vapor deposition, pulsed-laser deposition, and molecular beam epitaxy, spanning their development, as well as, advantages and disadvantages. Then, the up-to-date advances of 2DLM alloys in electronic devices are summarized. Subsequently, the up-to-date advances of 2DLM alloys in optoelectronic devices are summarized. In the end, the ongoing challenges of this emerging field are highlighted and the future opportunities are envisioned, which aim to navigate the coming exploration and fully exert the pivotal role of 2DLMs toward the next generation of electronic and optoelectronic devices.

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“…Eventually, the blue CDs can be stored in air at normal temperature and pressure for a long time, which indicates that the blue CDs are easy to preserve and the blue CDs are also stable materials with the short wavelength emission for LEDs. [25][26][27][28][29][30] Table S1 (Supporting Information) summarizes the key optical parameters of LEDs based quantum dots and CDs, including the corresponding half lifetime and EQE of solution-processing LEDs. Our work for blue CDs-LEDs opens a new way for low cost, good stability and high performance for the development of LEDs.…”

Section: Electroluminescence Mechanism Of Carbon Dots Light-emitting Diodesmentioning

confidence: 99%

“…[16][17] Recently, CDs have paved a new way for the development of LEDs due to high photoluminescence quantum yield (PLQY), fluorescence stabilization, hard to photobleaching, adjustable excitation wavelength and emission wavelength and good solubility. [15,[18][19][20][21][22][23][24][25][26][27][28][29][30] Kang et al successfully manufactured bright violet CDs-LEDs with PLQY of 23.9% and the highest luminance of 163 cd m -2 . [31] Ultra-bright and blue CDs-LEDs owned the PLQY of 88.9% and the highest brightness of 648 cd m -2 were produced as well, whose external quantum efficiency (EQE) reached to 2.114%.…”

Section: Introductionmentioning

confidence: 99%

Highly stable and bright blue light-emitting diodes based on carbon dots with a chemically inert surface

Zhang

Wang

et al. 2021

Nanoscale Adv.

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Fluorescent Carbon Dots: Fantastic Electroluminescent Materials for Light‐Emitting Diodes

Cited by 192 publications

References 146 publications

Optical Properties of Carbon Dots in the Deep‐Red to Near‐Infrared Region Are Attractive for Biomedical Applications

Optical Properties of Carbon Dots in the Deep‐Red to Near‐Infrared Region Are Attractive for Biomedical Applications

2D Layered Material Alloys: Synthesis and Application in Electronic and Optoelectronic Devices

Highly stable and bright blue light-emitting diodes based on carbon dots with a chemically inert surface

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