Issue 42, 2022

Ultrafast insights into full-colour light-emitting C-Dots

Abstract

Designing carbon dots (C-Dots) in a controlled way requires a profound understanding of their photophysical properties, such as the origin of their fluorescence and excitation wavelength-dependent emission properties, which has been a perennial problem in the last few decades. Herein, we synthesized three different C-Dots (blue, green, and red-emitting C-Dots) from the same starting materials via a hydrothermal method and separated them by silica column chromatography. All the purified C-Dots exhibited three different emission maxima after a certain range of different excitations, showing a high optical uniformity in their emission properties. It was also observed that the average distributions of the particle size in all the C-Dots were the same with a typical size of 4 nm and the same interplanar d spacing of ∼0.21 nm. Here, we tried to establish a well-defined conclusive answer to the puzzling optical properties of C-Dots via successfully investigating the carrier dynamics of their core and surface state with a myriad use of steady-state, time-resolved photoluminescence, and ultrafast transient absorbance spectroscopy techniques. The ultrafast charge-carrier dynamics of the core and surface state clearly indicated that the graphitic nitrogen in the core state and the oxygen-containing functional group in the surface state predominately contribute to controlling their wide range of emission properties. We believe that these findings will give the C-Dots their own designation in the fluorophore world and create a new avenue for designing and developing C-Dot-based new architectures.

Graphical abstract: Ultrafast insights into full-colour light-emitting C-Dots

Supplementary files

Article information

Article type
Paper
Submitted
24 Aug. 2022
Accepted
05 Okt. 2022
First published
06 Okt. 2022

Nanoscale, 2022,14, 15812-15820

Ultrafast insights into full-colour light-emitting C-Dots

N. Ghorai, S. Bhunia, S. Burai, H. N. Ghosh, P. Purkayastha and S. Mondal, Nanoscale, 2022, 14, 15812 DOI: 10.1039/D2NR04642C

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