Functionalization of Hydrophilic and Amphiphilic Carbon Dots with Polyethylene Glycol for Electroluminescent Devices

Small Structures, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 17, 2025

Carbon dots (CDs) are fluorescent carbon nanomaterials that considered for applications in optoelectronics, sensorics, and biofields due to their low‐cost robust synthesis, versatile optical properties. Herein, it is demonstrated how chemical functionalization of hydrophilic or amphiphilic CDs with polyethylene glycol influences energy level structure hence the emission Functionalization results an increase quantum yield: from 30% 75% 20% 25% CDs. The estimated absolute values levels, including highest occupied molecular orbital lowest unoccupied energies, dependent on composition size Moreover, glycol‐functionalized CD can form good quality films based composite polyvinylcarbazole (PVK), together intense crucial light‐emitting diode (LED) fabrication. By studying spectral properties fabricated CD‐LEDs, shown electroluminescence (EL) originates mixed levels PVK composite, resulting shifting EL maximum blue green during several seconds LED operation. optimized CD‐LEDs show brightness up 2600 cd m −2 .

Language: Английский

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Post‐Synthetic Graphitization and Photoluminescence Tuning of Carbon Dots from L‐Glutamic Acid

Small Structures, Journal Year: 2025, Volume and Issue: unknown

Published: Feb. 5, 2025

Carbon dots are promising luminescent nanostructures. Their availability, based on inexpensive precursors and their intrinsic fluorescent nature, place them as potential choices against traditional quantum in some applications. However, the carbon nature is nowadays not well defined understood. They usually hybrid nanomaterials terms of structure composition, which hinders knowledge photoluminescence mechanisms. Herein, solvent‐free pyrolysis L ‐glutamic acid by microwave synthesis leads to an incomplete graphitization precursor resulting loose polymer‐like nanohybrids. Further experiments confirm that these (CD) can be crosslinked graphitized a second heating step when using temperatures above 160 °C, reaching plateau over 200 °C. An exhaustive analysis thermogravimetric analysis, Raman X‐ray photoelectron spectroscopy highlights structural changes undergo from 140 where increase stability observed due process. The condensation decarboxylation reactions with loss hydrophilic functional groups like amine carboxylic acids explain formation sp 2 domains concomitant solubility. annealed CD exhibit broader slightly red‐shifted emission band, lower yields, compared initial

Language: Английский

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Vacuum-Assisted Synthesis of Solid-State Fluorescent Carbon Quantum Dots for Color Conversion LEDs

ACS Omega, Journal Year: 2025, Volume and Issue: unknown

Published: April 11, 2025

Carbon dots (CDs) are one of the most promising nanomaterials with tunable optical properties and very good biocompatibility, opening wide perspectives in sensing, imaging, optoelectronic applications. However, fluorescent CDs powder form that both adjustable effective remain a significant issue. Here, we describe simple, quick, scalable process for creating solid-state green-emissive using urea trisodium citrate dihydrate boric acid as matrix no dispersion solvent. The employs vacuum-assisted synthesis method, which enhances molecular interaction between precursors ensures uniform dispersion, significantly improving quality stability final product. embedded (B-CDs) exhibit photoluminescence quantum yield (PLQY) nearly 18% decrease when transitioning from aqueous solution to films. In contrast, without display lower PLQY luminescence solid state, highlighting enhancing effect matrix. By effectively reducing aggregation-induced quenching, matrix's spatial confinement is thought cause this rise fluorescence. resulting B-CD powders CIE coordinates have been used fabricate color-conversion light-emitting devices on UV chips. current study presents viable approach stable efficient. These will find extensive potential use luminescent based CDs, ranging flexible lighting systems color conversion, new era possibilities.

Language: Английский

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Synthesis of Blue-Emitting CuAlSe2 Quantum Dots and Their Luminescent Properties

Coatings, Journal Year: 2024, Volume and Issue: 14(10), P. 1291 - 1291

Published: Oct. 10, 2024

Quantum dot light-emitting diodes (QLEDs) have potential application prospects in new-type display fields due to their wide color gamut, high energy efficiency, as well low-cost mass production. Research on lead-free and cadmium-free blue quantum dots (QDs) is urgently needed for the development of QLED technology. For I-III-VI QDs, multiple luminescent centers generated by imbalanced local charge distribution a detrimental effect emission performance. Regulating chemical composition one effective methods control defect type blue-emitting QDs. In this work, narrow-bandwidth (with full width at half maximum 53 nm) CuAlSe2 QDs are achieved altering Cu/Al ratio. As ratio increases from 0.2 1, photoluminescence (PL) peak red-shifted 450 460 nm, with PL yield up 56%. The spectra deconvoluted into three peaks Gaussian fitting analysis, demonstrating main contribution coming radiative recombination electrons residing aluminum–copper antisite (AlCu) level holes valence band. This work provides new approach preparing eco-friendly high-efficient

Language: Английский

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Regulation of Electron Cloud Density by Electronic Effects of Substituents to Optimize Photocatalytic H₂ Evolution of Carbon Dots

Small, Journal Year: 2024, Volume and Issue: unknown

Published: Dec. 19, 2024

Abstract Carbon dots (CDs) have a wide light absorption range, which are promising candidates for photocatalytic water splitting H 2 evolution, but they show low activity hydrogen evolution reaction (HER) due to the slow transfer efficiencies of photogenerated carriers. The electron cloud density photocatalyst is essential separation and migration In this study, effect mechanism regulated by substituents with different electronic effects on HER glucose‐based CDs clarified. CDs‐SO 3 CDs‐OH first obtained introducing electron‐drawing group (─SO H) electron‐donating (─OH) using tailoring post‐processing strategy. Experimental results that yield catalyzed 89.95 µmol•g −1 in 4 h, about four times CDs, 7.4 CDs‐OH. ─SO induces much negative energy band high edges, promoting carriers; while exhibits positive charge an upward band, hindering surface complexation electron‐hole pairs HER. This study will provide insight into design catalysts efficient at molecular level.

Language: Английский

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Establishment of efficient system for bagasse bargaining: Combining fractionation of saccharides, recycling of high-viscosity solvent and dismantling

Bioresource Technology, Journal Year: 2024, Volume and Issue: unknown, P. 131482 - 131482

Published: Sept. 1, 2024

Language: Английский

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Development of Methylene Bis-Benzotriazolyl Tetramethylbutylphenol-Grafted Lignin Sub-Microspheres Loaded with TiO2 for Sunscreen Applications

Journal of Bioresources and Bioproducts, Journal Year: 2024, Volume and Issue: 9(4), P. 534 - 547

Published: Sept. 21, 2024

Language: Английский

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