Multicolour nitrogen-doped carbon dots: tunable photoluminescence and sandwich fluorescent glass-based light-emitting diodes

Abstract

The first use of the combination of ammonium citrate (AC) and ethylenediamine tetraacetic acid (EDTA) as coordinating precursors for the synthesis of highly fluorescent (quantum yield = 67%) multicolour nitrogen-doped carbon dots (CDs) is reported. Under UV light, these CDs emitted outstanding luminescence in colours from dark blue to red. Interestingly, a single component white-light CD point with high fluorescence efficiency was obtained by surface control. Alterations of the photoluminescence (PL) emission of these full-colour CDs were tentatively proposed to benefit from surface functional groups, such as C[double bond, length as m-dash]O and C[double bond, length as m-dash]N. An energy-level model was proposed to explain the continuously adjustable full-colour emission. The white light may be attributed to the overlap of diverse light emission induced by electron transitions between the energy levels. Subsequently, to avoid aggregation-induced solid-state fluorescence quenching, multicolour CD-based sandwich glasses with various colour emission was fabricated, which is anticipated to be compatible with the all-optical light-emitting diodes (LEDs). The facile preparation and outstanding optical features are believed to provide an alternative synthesis route and inspire more research into applications and CD-based materials of multicolour CDs.

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

“…The time‐resolved PL decay curve of each sample was also measured. The results (Figure f; Table S2, Supporting Information) show that they can be fitted by a dual‐exponential formula, involving a short‐lived component τ 1 (about 1 ns) and a long‐lived component τ 2 (about 10 ns), which are assigned to the recombination processes in the core states and the surface states, respectively . It is clear that from B‐CDs to R‐CDs, as the average lifetime decreases from 10.2 to 2.1 ns, the τ 1 proportion increases from 40% to 88%, indicating that the role of core states in the radiative lifetime of these CDs increases with their PL redshift .…”

Upconverting Carbon Nanodots from Ethylenediaminetetraacetic Acid (EDTA) as Near‐Infrared Activated Phototheranostic Agents

“…Thism olecular precursorh as been selected to induce the direct generation of nitrogen-doped carbon nanodots (N-CNDs) in as ingle step without the need for secondary amine co-reactants. [34][35][36][37] Previous works have claimed that partial substitution of Nw ithin the pseudo-graphitic structure of CNDs provides them with an expanded photoluminescence response. [34][35][36][37][38][39][40][41][42] In this work, we demonstrate that the N-CNDs formed from EDTAe xhibit excellent opticalp hotoluminescence (PL) properties in the whole UV/Vis/NIR range.…”

Orange‐Emissive Carbon Quantum Dots: Toward Application in Wound pH Monitoring Based on Colorimetric and Fluorescent Changing

“…The strong absorption peak at 296 nm in the spectrum was caused by the n–π* transitions of CO bonds. Despite the lower intensities, another absorption band appeared in the high‐energy region at 238 nm was related to the π–π* transition of the aromatic sp 2 bond . In addition, a distinct absorption band from 375 to 485 nm was also observed in the lower‐energy region; such absorption characteristic is usually considered to originate from the defect states caused by the functional groups on the CDs surfaces; the presence of defect states within the structures of O‐CDs can also be confirmed by the size independent PL emission.…”

“…Although plentiful researches have proposed that the structural defects help to create bandgaps within the structure of CDs, the relationship between structural defects and bandgaps is still controversial. In the view of long‐wavelength emissions, many previous efforts have indicated that the defect states originated from surface groups are highly responsible for energy gaps changes, and thus releasing energy in the forms of multiple PL emissions …”

“…The strong band at 1675 cm −1 could be related to the amide carbonyl . In addition, the bending vibration of CN (1311 cm −1 ), stretching vibration of COC (1168 cm −1 ), and asymmetric and symmetric stretching vibrations of CO (1211 and 1022 cm −1 ) were also determined from FTIR spectrum . The chemical composition and speciation of O‐CDs were also examined by X‐ray photoelectron spectroscopy (XPS), as shown in Figure F.…”