Highly Efficient Carbon Dots with Reversibly Switchable Green–Red Emissions for Trichromatic White Light-Emitting Diodes

Yuan, Biao; Guan, Shanyue; Sun, Xingming; Li, Xiaoming; Zeng, Haibo; Xie, Zheng; Chen, Ping; Zhou, Shuyun

doi:10.1021/acsami.8b02379

Cited by 161 publications

(99 citation statements)

References 68 publications

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“…The electroluminescence (EL) spectrum of the WLED shown in Figure 5c displays three emission bands centered individually at 452, 520, and 611 nm. The as‐synthesized WLED also showed color coordinates of 0.366 and 0.366 with a correlated color temperature (CCT) of 4333 K. It was remarkable to see that that the CRI of the WLED could reach a maximum of 93.5, performing better than most of CD‐based WLEDs and commercial lights (Table S3, Supporting Information) . As shown in Figure 5d, the WLED maintains great color rendering ability, with true picture colors under ambient light vividly reflected.…”

Section: Resultsmentioning

confidence: 99%

Scalable Synthesis of Green Fluorescent Carbon Dot Powders with Unprecedented Efficiency

Wei

Lou

Zang

et al. 2020

Advanced Optical Materials

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quantum yield (PL QY) of 93.3%; the highest yield to date among the blue-emitting CDs. [21] Sun and co-workers developed a CD synthesis technique using multicolored emission through controlled graphitization and surface functionalization. [1] They found the CD emission band to be tunable from 430 nm to 630 nm, which covers the blue and red region.Despite such large progress achieved for CD synthesis, plenty of barriers still exist to CD commercialization. Typically, CDs with great performance are primarily prepared through solvothermal routes, meaning at least several hours are needed to prepare CDs at milligram levels. [1,3,4,6,[19][20][21][22][23] Nevertheless, expensive precursors and complex purification processes will no doubt enlarge the construction costs and increase the preparation time. [3][4][5][6] In another way, CDs suffer from aggregation-causedquenching (ACQ) due to π-π stacking in the solid state, which has shown to greatly hinder the application of CDs in light-emitting fields. [24][25][26][27][28] To overcome this deficiency, efforts have been targeted to develop solid CDs with efficient fluorescence by way of CD monomer separation from direct contact, including CD implantation inside polymer matrices and combining them with inorganic salts as composites. [29][30][31][32][33][34][35][36][37][38] Although this effectively prevents the ACQ of CDs in solid state by the dispersal of CDs into various matrices, only CDs at lower loading fractions (i.e., <0.2 wt%) have the ability to achieve high PL QY. [39] While most white LEDs (WLEDs) are created using the one-step synthesis of white light-emitting CDs, the down-conversion fluorescent powders usually suffer from low luminous efficiency or color instability. [40][41][42] Therefore, it is paramount to develop solid CDs with high fluorescence efficiency and stability in facile, low cost, and high-output ways in order to satisfy scale-up industrial production and application.In this study, we report a facile one-step microwave-assisted heating method to prepare solid CDs with strong green emissions. Here, citric acid, urea, and sodium hydroxide (NaOH) have been used as precursors. The CDs were also made to be resistant to self-quenching by in situ embedding the CD into the crystal matrix of NaOH, so that the PL QY could reach 75.9% in the solid state. To the best of our knowledge, this is the highest value attained for solid CDs having green emission. [8,32,[35][36][37][38] Moreover, powdered CD (CDPs) would also have the potential to be prepared on a much larger scale in several minutes It still remains a challenge to synthesize solid-state carbon dots (CDs) with high emission efficiency; a hurdle that has hindered the application of CDs in many fields. In this work, efficient fluorescent CDs have been prepared through a one-step microwave-assisted heating method. Experimental data show strong green emissions produced from the CD powders (CDPs), carrying an unprecedented 75.9% quantum yield due to both spatial confinement and defect reduction with the ...

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Section: Resultsmentioning

confidence: 99%

Scalable Synthesis of Green Fluorescent Carbon Dot Powders with Unprecedented Efficiency

Wei

Lou

Zang

et al. 2020

Advanced Optical Materials

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“…By comparison, the RCDs have highest carboxyl contents, leading to more surface defects and narrower energy gap. Besides that, Zhou groups also demonstrated a kind of CDs with switching ability between reversible green and red photoluminescence via controlling oxidation degree under alkaline conditions . On the other hand, grafting amine groups (−NH 2 ) to the surface of graphene quantum dots (GQDs) also can tune photoluminescence and obtainment of RCDs .…”

Section: Influencing Factors On the Rcdsmentioning

confidence: 99%

Synthesis and Applications of Red‐Emissive Carbon Dots

Wang

Zhu

Wang

2019

The Chemical Record

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Carbon dots (CDs), a new class of fluorescent carbon nanoparticles (less than 10 nm in size), have been widely applied in various fields, including sensors, bioimaging, catalysis, lightemitting devices (LEDs), and photoelectronic devices, owing to their unique properties such as low toxicity, bio-compatibility, high photostability, easy surface modification, and up-conversion fluorescence, over the past decades. Recently, multiple-color-emissive CDs, especially redemissive CDs (RCDs), have drawn much attention owing to their unique advantages, like the ability to penetrate the animal bodies without the disturbance of strong tissue autofluorescence, multiple-color fluorescence displaying or sensing, and the capacity to be one essential component to obtain white LED (WLED). In this review, we focused on the progress of recently-emerging RCDs in the past five years, including their synthetic methods (hydrothermal, solvothermal, reflux condensation and microwave techniques), influencing factors (precursors, solvents, elements doping, surface chemistry) and various applications (bioimaging, sensor, photocatalysis and WLEDs), with a perspective on the future advancements.

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“…粉、半导体QDs, CQDs等 [11,12] . Figure 3 (Color online) Solid-state quenching mechanism of CQDs and fluorescence recovery mechanism of CQD/SiO 2 composite [37] 2017年, Wang等人 [52] 以二羟基萘为原料, 通过溶 [52] 2019 年 5 月第 64 卷第 14 期…”

Section: 目前应用于Wled的荧光粉主要有稀土荧光unclassified

“…, 自从2006 年首次被发现以来 [4] , . 目前, CQDs的发光波长已经可以由深紫外区扩展到近红外区 [9] , 且蓝、绿、红光 C Q D s 的 Q Y 最高分别已经高达 9 9 % ， 8 1 % 和 80% [10,11] . 由于其具有较高的电子迁移率、较长的热电子寿命、宽的光学吸收, 使其在白光发光二极管(white light-emitting diode, WLED) [12~14] 、QDs电致发光二极管(QD-based electroluminescent light-emitting diode, QLED) [15~17] 、激光二极管(laser diode, LD) [18,19] 、可见光通信(visible light communication, VLC) [12,13] 、聚合物太阳能电池(polymer solar cell, PSC)…”

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