Color Emission Carbon Dots with Quench-ResixAstant Solid-State Fluorescence for Light-Emitting Diodes

Abstract

Since carbon dots (CDs) were reported in 2004, they have been widely used in various fields due to their outstanding optical properties. However, most CDs are self-quenched due to the direct π−π interaction in the solid-state aggregation. This shortcoming limits the wide application of CDs, because numerous optoelectronic devices and sensors usually require photoluminescent materials in the solid state. Therefore, designing and preparing carbon dots with multicolor solid emission is necessary. Here, solid-state fluorescence (SSF) CDs were prepared via a one-step solvothermal method, using MA and APTES as raw materials. Through adjusting the ratio of raw materials, solid-state emitting CDs with green, yellow, and orange colors are obtained. The fluorescence spectrum ranges from 490−625 nm, and the QYs are 34.06%, 38.07%, and 20.37%, respectively. For prepared CDs, the main reason for the solid-state emission is that the Si−O, Si−C, and Si−N bonds generated during the formation process can prevent the π−π interaction between the graphitized cores. The red shift mechanism of solid and liquid fluorescence is attributed to the decrease in particle size and the increase in the degree of particle aggregation within the unit range. In addition, based on these excellent photoluminescence properties, we have prepared colored light-emitting diodesthe CIEs are (0.22, 0.41), (0.38, 0.47), and (0.50, 0.43) (Commission Internationale de l'Elcairage coordinate)and solid-state emitting CDs/epoxy films with high transparency and stability.

Gram‐Scale Synthesis of Highly Efficient Rare‐Earth‐Element‐Free Red/Green/Blue Solid‐State Bandgap Fluorescent Carbon Quantum Rings for White Light‐Emitting Diodes

“…The absolute QYs of R/G/B-SBF-CQRs are measured to be 38 %, 46 %, and 30 % for B-, G-, and R-SBF-CQRs, respectively, which are higher than the QY values previously reported for blue/red solid-state fluorescent CQDs. [12][13][14][15][16] As shown in Figure 2 S1 in the Supporting Information) and increase in the lowest unoccupied molecular orbital (LUMO) level from 2.45 to 2.95 eV directly reveal the bandgap transitions in SBF-…”

Gram‐Scale Synthesis of Highly Efficient Rare‐Earth‐Element‐Free Red/Green/Blue Solid‐State Bandgap Fluorescent Carbon Quantum Rings for White Light‐Emitting Diodes

“…The absolute QYs of R/G/B-SBF-CQRs are measured to be 38 %, 46 %, and 30 % for B-, G-, and R-SBF-CQRs, respectively, which are higher than the QY values previously reported for blue/red solid-state fluorescent CQDs. [12][13][14][15][16] As shown in Figure 2 S1 in the Supporting Information) and increase in the lowest unoccupied molecular orbital (LUMO) level from 2.45 to 2.95 eV directly reveal the bandgap transitions in SBF- CQRs. As shown in Figure 2 d, the PL decay of R/G/B-SBF-CQRs is monoexponential with a relatively long lifetime of 10.5, 11.3, and 12.5 ns for B-, G-, and R-SBF-CQRs, respectively, which is conducive for efficient fluorescence emission.…”

Preparation of multicolor-emissive carbon dots with high quantum yields and their epoxy composites for fluorescence anti-counterfeiting and light-emitting devices

“…15 Yan 4 Obviously, many studies have shown that the solvothermal method is the most commonly used method to prepare multicolor CDs owing to a wide range of precursors and alternative synthesis conditions. [17][18][19] However, the low relative QY of long wavelength light-emitting CDs and the harsh reaction conditions for preparing CDs such as high temperature and long reaction time seriously restrict the practical applications of CDs for LEDs, vivo imaging, and so on. From this perspective, it is strongly required to develop a facile method to prepare high QY CDs with full-color-emission under mild reaction conditions.…”