Rational Design of Full-Color Fluorescent C₃N Quantum Dots

Abstract

Carbon-based quantum dots (QDs) exhibit unique photoluminescence due to size-dependent quantum confinement, giving rise to fascinating full-color emission properties. Accurate emission calculations using time-dependent density functional theory are a time-costing and expensive process. Herein, we employed an artificial neural network (ANN) combined with statistical learning to establish the relationship between geometrical/ electronic structures of ground states and emission wavelength for C 3 N QDs. The emission energy of these QDs can be doubly modulated by size and edge effects, which are governed by the number of C 4 N 2 rings and the CH group, respectively. Moreover, these two structural characteristics also determine the phonon vibration mode of C 3 N QDs to harmonize the emission intensity and lifetime of hot electrons in the electron−hole recombination process, as indicated by nonadiabatic molecular dynamics simulation. These computational results provide a general approach to atomically precise design the full-color fluorescent carbon-based QDs with targeted functions and high performance.

Polarized local excitons assist charge dissociation in Y6-based nonfullerene organic solar cells: a nonadiabatic molecular dynamics study

“…, by the fewest-switches algorithm. 64–66 It may be interesting to also apply the surface hopping method to study the nonadiabatic effects particularly when the system exists in a well localized nonadiabatic coupling region. Note that both the Ehrenfest method and surface hopping may seriously underestimate the dephasing time, due to treating nuclei classically.…”

High-purity C3N quantum dots for enhancing fluorescence detection of metal ions

“… 31 Recently, Yang et al 27 have utilized a conventional hydrothermal method to synthesize the C 3 N QDs with a relatively long lifetime, and tuned the PL of C 3 N QDs over the entire visible range (400–660 nm) up to the IR region based on the size dependence of the bandgap. Pei et al 32 have found that the emission energy of C 3 N QDs can be doubly modulated by size and edge effects through an artificial neural network (ANN) combined with statistical learning. They have established the relationship between geometrical/electronic structures of ground states and emission wavelength for C 3 N QDs, and provided a general approach to atomically precise design the full-color fluorescent carbon-based QDs with targeted functions and high performance.…”

Unraveling the Photocatalytic Mechanism of N2 Fixation on Single Ruthenium Sites

“…Figure b shows photogenerated electrons are excited from HOMO orbital to high excited states. Nevertheless, the energetic electron in the high excited states is unstable; it will return the electron back to the photocatalyst and relax to the LUMO rapidly via internal conversion and vibrational energy states with time scale of 10 –5 –10 –2 ns. , Hence, we assumed that photogenerated electron was excited to high energy level forming the high excited states. Subsequently, it will undergo relaxation to either the antibonding π* orbitals of *N 2 or LUMO of ligand-protected NCs, marked as processes ① and ②, respectively.…”