Carbon Nanodots with Nearly Unity Fluorescent Efficiency Realized via Localized Excitons

Abstract

Carbon nanodots (CDs) have emerged as an alternative option for traditional nanocrystals due to their excellent optical properties and low toxicity. Nevertheless, high emission efficiency is a long-lasting pursuit for CDs. Herein, CDs with near-unity emission efficiency are prepared via atomic condensation of doped pyrrolic nitrogen, which can highly localize the excited states thus lead to the formation of bound excitons and the symmetry break of the 𝝅-electron conjugation. The short radiative lifetimes (<8 ns) and diffusion lengths (<50 nm) of the CDs imply that excitons can be efficiently localized by radiative recombination centers for a defect-insensitive emission of CDs. By incorporating the CDs into polystyrene, flexible light-converting films with a high solid-state quantum efficiency of 84% and good resistance to water, heating, and UV light are obtained. With the CD-polymer films as light conversion layers, CD-based white light-emitting diodes (WLEDs) with a luminous efficiency of 140 lm W −1 and a flat-panel illumination system with lighting sizes of more than 100 cm 2 are achieved, matching state-of-the-art nanocrystal-based LEDs. These results pave the way toward carbon-based luminescent materials for solid-state lighting technology.

Carbon Nanodots Memristor: An Emerging Candidate toward Artificial Biosynapse and Human Sensory Perception System

“…Reproduced with permission. [ 84 ] Copyright 2022, Wiley. c) The synthetic procedures of CDs and their application in logic chemosensing.…”

“…However, the information emission disappeared under 655 nm excitation, due to the transition from CNRs to CNBs. These CDs derivatives with different shapes and morphologies indicated [84] Copyright 2022, Wiley. c) The synthetic procedures of CDs and their application in logic chemosensing.…”

“…b) Structure and properties of the CD-based electroluminescent device. Reproduced with permission [84]. Copyright 2022, Wiley.…”

Supramolecular Chemistry of Carbon‐Based Dots Offers Widespread Opportunities

“…The earliest report are significant opportunities to afford specific structures and/or properties for further applications, not only by starting with the appropriate reagents, but also by post-functionalization of the as-prepared nanomaterial. [14,15] Especially the choice of the precursors and reaction conditions in the bottom-up syntheses has a profound effect on the final structure and properties of CDs: surface groups, [2,16] optoelectronic and electrochemical properties, [17][18][19][20][21][22][23][24][25][26][27] chirality, [28][29][30] and so on.…”

Biosynthesis of the Narrowband Deep-Red Emissive Carbon Nanodots from Eggshells

“…3a, the XRD patterns of the CND powder have two broad peaks at 9 and 23°, which are attributed to the scattering of graphite (001) and (002), respectively. 42,43 The FTIR spectra of the CND powders clearly indicate the presence of various functional groups (Figure 3b). The broad absorption bands at 3000−3500 cm −1 are attributed to the characteristic O−H and N−H stretching vibrations, 25,34,44 while the peak around 2900 cm −1 is related to the −CH 2 − symmetrically stretching vibration.…”