Multicolor-Emissive Carbon Dots for White-Light-Emitting Diodes and Room-Temperature Phosphorescence

Abstract

Multicolor tuning is one of the most remarkable features of carbon dots (CDs), used as a color convertor in making white-light-emitting diodes (WLEDs). Herein, a solvent-controlled method has been employed to prepare the multicolor-emissive CDs from 1,2,4-triaminobenzene and melamine, where the green-, orange-, and red-color-emissive carbon dots (G-, O-, and R-CDs) have been synthesized in acetone, water, and dimethylformamide (DMF), respectively. It has noted that the reaction solvent has impacted the growth of the particle size, elemental concentration, surface functionalization, and ultimately fluorescence emission. To avoid aggregation quenching emission (AQE), fluorescent polymeric films have been shaped by mixing poly(methyl methacrylate) (PMMA) with R-and G-CDs, while O-CDs was made with poly(vinyl alcohol) (PVA). Interestingly, PVA exhibited red-shifted emission of O-CDs from 585 to 597 nm in O-CDs/ PVA, while PMMA accompanied a blue-shifting emission. The enriched nitrogen and oxygen elemental contents, especially the graphitic N of O-CDs/PVA, and hydrogen-bonding affinity of PVA cause the red-shifted emission of O-CDs/PVA. Fluorescent solid films have been used to develop monochromatic and white-color-emissive light-emitting diodes. Further, all of the synthesized CDs served as carbon precursors to develop room-temperature phosphorescence (RTP) by a molten salt method, where only R-and O-CDs achieved their RTP emissions with different intensities. The mechanism behind the RTP formation with particular CDs and their emission intensity dependency has been studied by the C�O moieties.

One-Pot Synthesis of Trichromatic Fluorescent Carbon Dots for Printing and Imaging

“…11,12 Furthermore, the preparation methods of multicolor CDs have attracted considerable interest. Fluorescent CDs with different wavelengths can be obtained by adjusting the types and concentrations of precursors and reaction solvents 13,14 and changing the reaction temperature or changing several reaction conditions simultaneously. 15,16 Although these studies have prepared CDs emitting different colors, the colors presented are random, unpredictable, and difficult to regulate.…”

“…Owing to these unique properties and various applications, fluorescent CDs have been developed in various ways, for example, an electrochemical oxidation method, solvothermal method, template method, and microwave method. , Furthermore, the preparation methods of multicolor CDs have attracted considerable interest. Fluorescent CDs with different wavelengths can be obtained by adjusting the types and concentrations of precursors and reaction solvents , and changing the reaction temperature or changing several reaction conditions simultaneously. , Although these studies have prepared CDs emitting different colors, the colors presented are random, unpredictable, and difficult to regulate. In addition, most of these methods use high temperature and pressure preparation conditions, which makes the process difficult and unsafe.…”

Modulating multi-color room temperature phosphorescence emission for carbon dot composites with ultralong lifetime

“…[14][15][16][17][18][19][20][21][22] In general, the optical properties of RTP CDs can be enhanced effectively by heteroatom doping that include F, 23 N, 24 P, 25 S, 26 etc. Besides, matrix-assisted synthesis is another important method to obtain RTP CDs by embedding CDs into a matrix such as cyanuric acid, 27 SiO 2 , 28 melamine, 29 polyvinyl alcohol (PVA) 30 and so on. Recently, inspiring progress has been made using both methods.…”

Construction of composite films using carbon nanodots for blocking ultraviolet light from the Sun

“…9 With the development of UV blocking materials, carbon nanodots (CNDs) have gradually been used to block high-energy short wavelength light due to their excellent optical absorption and conversion properties. 1,2,10,11 CNDs are a new type of carbon nanomaterial with a particle size <10 nm, excellent resistance to photobleaching and good responsiveness to changes in pH and temperature, [12][13][14][15][16] which are widely used in white light emitting diodes (WLEDs), [17][18][19][20] in anticounterfeiting applications, 21,22 as probes, [23][24][25] and catalysts, 26,27 and for biological imaging. 28,29 Among the many possible sources of carbon for preparing carbon dots, natural resources and derivatives are particularly attractive because of their abundance, low price, environmental friendliness and sustainability.…”