Yellow‐Emissive Carbon Dots with High Solid‐State Photoluminescence

Abstract

Carbon dots (CDs) present an enticing prospect for a variety of optical applications relying on their high photoluminescence (PL) quantum yield (QY). Herein, the synthesis, optical properties, structural characterizations, density‐functional theory (DFT) calculations, and potential applications of yellow‐emissive CDs (Y‐CDs) with ultra‐high PL QY are reported. Solvothermal treatment of citric acid and urea in toluene, followed by column chromatography, produces Y‐CDs exhibiting excitation‐independent PL emission at 553 nm with a high solution PL QY of 92%. A variety of optical and structural characterizations and DFT theoretical calculations are implemented to confirm the general structure and fluorescence origin of Y‐CDs, conjugated sp2‐carbon domains (fused rings) with edge groups. Significantly, transparent Y‐CDs/acrylic resin films with strong solid‐state emissions are fabricated. The Y‐CD films exhibit a high fluorescence with PL QY of 98%, good PL stability (no PL variation under continuous irradiation for 180 h), and large Stokes shift (129 nm). The potential applications of Y‐CDs for luminescent solar concentrators as well as yellow phosphors for lighting are also demonstrated. These findings thus promote the development of high‐performance CDs and their optoelectronic applications.

Citric Acid-Based Carbon Dots and Their Application in Energy Conversion

“…As reported so far, all CA/U-CDs obtained by pyrolysis, microwave irradiation, or hydrothermal treatment display blue or green fluorescent emission, which originates from individual molecular fluorophores as well as from their self-assembly into H-bonded or covalently linked aggregates. Interestingly, CA/U-CDs with emission at longer wavelengths have also been achieved by replacing water with DMF ,− ,, or toluene . In the work of Hu et al, it is shown that the autoclave thermal treatment of 1.0 g of citric acid and 2.0 g of urea in 10 mL of DMF can produce CA/U-CDs with tunable emission, from blue to red, by increasing the reaction temperature .…”

“…Interestingly, CA/ U-CDs with emission at longer wavelengths have also been achieved by replacing water with DMF 18,78−80,89,90 or toluene. 91 In the work of Hu et al, it is shown that the autoclave thermal treatment of 1.0 g of citric acid and 2.0 g of urea in 10 mL of DMF can produce CA/U-CDs with tunable emission, from blue to red, by increasing the reaction temperature. 80 Similar observations are present in the work of Miao et al, who also reported that higher citric acid/urea ratios can red-shift the final CA/U-CD emission.…”

Nitrogen-Doped Ti3C2 MXene Quantum Dots/1D CdS Nanorod Heterostructure Photocatalyst of Highly Efficient Hydrogen Evolution

“…The N 1s spectra (Figure d) present three peaks located at 397.7, 398.6, and 399.6 eV, corresponding to the Ti–N bond, pyridinic N and pyrrolic N, further confirming the successful doping of nitrogen. − The Ti 2p spectrum of N-MQDs/CdS exist five peaks, which belong to Ti–N bond (456.4 eV), Ti-Cbond (461.3, 455.4 eV) and Ti–O bond (464.4, 458.5 eV). , Apparently, the formation of Ti–N confirms the successful N doping in Ti 3 C 2 MXene quantum dots (Figure e). The C 1s spectra of pure CdS (Figure S9) show peaks at 284.7, 286.2, and 288.8 eV attributed to C–C/CC, C–O, and CO bonds, respectively . Compared with pure CdS, the extra peak in N-MQDs/CdS at 283.8 eV attributed to C–Ti bond (Figure f), which further evidence the successful compounding of N-MQDs and CdS.…”

Toward Strong Near‐Infrared Absorption/Emission from Carbon Dots in Aqueous Media through Solvothermal Fusion of Large Conjugated Perylene Derivatives with Post‐Surface Engineering

“…[ 6 ] To date, various CDs have been developed and efficient blue, green, and red emissions have been achieved in several CDs systems. [ 7 ] However, efficient NIR‐emissive CDs have rarely been reported. [ 8 ] The initial attempt was to synthesize NIR‐emissive CDs from high price NIR‐emissive organic dyes.…”