Solvent‐Controlled Synthesis of Highly Luminescent Carbon Dots with a Wide Color Gamut and Narrowed Emission Peak Widths

Abstract

Carbon dots (CDs) have tremendous potential applications in bioimaging, biomedicine, and optoelectronics. By far, it is still difficult to produce photoluminescence (PL) tunable CDs with high quantum yield (QY) across the entire visible spectrum and narrow the emission peak widths of CDs close to those of typical quantum dots. In this work, a series of CDs with tunable emission from 443 to 745 nm, quantum yield within 13-54%, and narrowed full width at half maximum (FWHM) from 108 to 55 nm, are obtained by only adjusting the reaction solvents in a one-pot solvothermal route. The distinct optical features of these CDs are based on their differences in the particle size, and the content of graphitic nitrogen and oxygen-containing functional groups, which can be modulated by controlling the dehydration and carbonization processes during solvothermal reactions. Blue, green, yellow, red, and even pure white light emitting films (Commission Internationale de L'Eclairage (CIE)= 0.33, 0.33, QY = 39%) are prepared by dispersing one or three kinds of CDs into polyvinyl alcohol with appropriate ratios. The near-infrared emissive CDs are excellent fluorescent probes for both in vitro and in vivo bioimaging because of their high QY in water, long-term stability, and low cytotoxicity.

Near-infrared emissive carbon dots with 33.96% emission in aqueous solution for cellular sensing and light-emitting diodes

“…At present, most of the known CDs produce blue to green emissions with ultraviolet or blue excitation, which limits their multi applications [15][16][17][18]. The development of more environmentally friendly synthesis methods for the efficient and controllable preparation of red-emitting CDs with high quantum yields in aqueous solutions is crucial [19][20][21].…”

Facet-Dependent Interfacial Charge Transfer in TiO2/Nitrogen-Doped Graphene Quantum Dots Heterojunctions for Visible-Light Driven Photocatalysis

“…Figure S4 shows the TEM image of NGQDs, which has an average size of ~2.4 nm. Clear lattice fringes demonstrative of its well-crystalline structure, and the autocorrelated HRTEM lattice image (inset in Figure S4b) show a 0.21 nm lattice fringe assigned to the {100} plane of GQDs [39,40].…”

Surface modification strategy for fluorescence solvatochromism of carbon dots prepared from p-phenylenediamine

“…The absolute PL QYs of the DA-CDs and PFDA-CDs were lower than that of the CDs, which is attributed to the following three factors. The first factor is non-radiative relaxation through vibration of the p-conjugated structure caused by vibration of the long-chain alkyl or perfluoroalkyl group, as described in a previous report, 6 where non-radiative relaxation was inhibited by an increase in the rigidity of the p-conjugated structure in CDs. The second factor is the decreased amount of amino groups due to the conversion of amino groups to amide bonds through surface modification because amino groups play a role in surface passivation.…”

“…3 Because of these advantages, CDs are also good alternatives to organic dyes. CDs have been demonstrated to have applications as spectral converters for near-UV and blue light-emitting diodes, 4,5 fluorescent bio-markers in bioimaging, 6,7 and sensors for the toxic metal ion Hg 2+ . 8 Most previous works have reported blue-emitting CDs.…”

“…[9][10][11] Studies on the production of multi-colour emission in addition to blue have been started recently. The following three important factors affect the emission wavelength of CDs: p-conjugated domain size related to the particle size and graphitization degree, 5,12,13 heteroatom doping, 6,14,15 and surface functional groups. 16,17 It is difficult to manage these factors independently; therefore, strategies for controlling the emission colours of CDs have not been established thus far.…”