Anhydride-Terminated Solid-State Carbon Dots with Bright Orange Emission Induced by Weak Excitonic Electronic Coupling

Abstract

In this work, fluorescent solid carbon dots (CDs) welcome a new member, namely anhydride-terminated CDs, which have a photoluminescence quantum yield (PLQY) of 28% for orange-emitted CDs at 580 nm in powder form. For the first time, we revealed that the electronic coupling of the functional groups should be a crucial factor affecting the optical properties of solid CDs. Due to the negligible hydrogen bonding interaction between the anhydride groups, the electronic coupling of excitons between neighboring anhydride groups is weak, leading to a high PLQY of 28% and an immobile emission peak at 580 nm in solid state. Anhydride-terminated CDs can be partly converted into carboxyl-terminated CDs after dispersion in ethanol. However, the strong electronic coupling of carboxyl groups at high concentration generates the stacking mode of J-aggregates, giving rise to a red-shifted emission from 450 to 515 nm as well as quenched fluorescence in solid state. In comparison, a useful blue emission for solid-state CDs occurs from low sp 2 hybridized carbon atoms, which possess weak electronic coupling and a stationary emission band at 450 nm in both solution and solid state. By adjusting the feed ratio of the reactants, the relevant intensities between the emission from low sp 2 hybridized carbon atoms at 450 nm and the emission from anhydride groups at 580 nm can be controlled. As a result, singlecomponent anhydride-terminated CD powder with tunable emission color from orange to white light can be achieved. As-prepared anhydride-terminated CDs can be used for fabricating light-emitting diodes (LEDs), white LEDs, and luminescent solar concentrators (LSCs).

Post-synthetic regulation of the fluorescence of CDs: insights into the fluorescence mechanism

“…According to FTIR results, only the stretching vibration peak of the carbonyl group (CO) at 1750–1680 cm −1 (ref. 26) (Fig. 3B) and the stretching vibration peak of the carbonyl group (CO) in amide at 1650–1600 cm −1 (ref.…”

Facile Preparation Strategy of Novel Carbon Dots with Aggregation‐Induced Emission and Room‐Temperature Phosphorescence Characteristics

“…As shown in Figure a, the UV−Vis absorption of the as‐prepared E‐CCDs displayed a dominating band at 560 nm, which can be attributed to the n–π* transitions of the surface states containing CN/CO, CO and CS structures. [ 16a ] A weak peak at 345 nm was also observed, corresponding to the π–π * transitions of the CC in the carbonaceous core. Impressively, the E‐CCDs sample (orange powders under daylight) exhibits red fluorescence emission excited by 365 nm UV light (inset in Figure 2a).…”

“…[ 15 ] The Raman spectrum of the E‐CCDs (Figure S3, Supporting Information) exhibited two characteristic peaks at 1344 cm −1 (D band) and at 1576 cm −1 (G band), corresponding to the disordered structures and graphitic structures of carbon materials respectively. [ 16 ] The intensity ratio of I G / I D is ≈1.12, indicating that the CDs have a good degree of graphitization.…”

Synthetic strategies, properties and sensing application of multicolor carbon dots: recent advances and future challenges

“…Since then, developing fascinating CDs with versatile properties has received great attention in many fields. [7][8][9][10][11] The most predominant characteristic of CDs is that they have remarkable properties, such as tunable photoluminescence, 12 high fluorescence quantum yield (QY), 13,14 ease of surface functionalization, 15 good aqueous solubility, 16 superior biocompatibility, 17 and high photostability, 18,19 have received immense research attention, which enables CDs to be an excellent alternative to semiconductor quantum dots (QD) with a wide variety of promising applications in the fields of sensing, 20 bioimaging, 21 biomedicine, 22 electronic devices, 23 and anti-counterfeiting. 24 In the initial development stage of CDs, the main research focuses on the preparation of carbon dots, utilizing a large number of carbon sources and numerous approaches.…”