Theoretical study on the optical and electronic properties of graphene quantum dots doped with heteroatoms

Abstract

The effects of four heteroatoms (B, N, P, and S) with three doping patterns on graphene quantum dots (GQDs) are systematically investigated using time-dependent density functional theory (TD-DFT). The absorption spectra and HOMO-LUMO gaps are quantitatively analyzed to study the correlations between the optical properties and heteroatom doping of doped GQDs. Heteroatom doping can endow GQDs with various new optical and structural properties, depending on the dopants and doping configurations. Compared with the absorption spectra of pristine GQD, both N and S surface doping demonstrate a slight blue shift, whereas B and P doping lead to a blue shift for edge-doped GQDs with heteroatoms in a pentatomic ring. The absorption process is investigated along with excited state analysis, which includes the density of state, natural transition orbital, and charge difference density. The results indicate that large radius atoms assist charge transfer in the excited state and play an important role in recombining the electron density distribution in the doped GQDs.

Anticancer Photodynamic Therapy Properties of Sulfur‐Doped Graphene Quantum Dot and Methylene Blue Preparations in MCF‐7 Breast Cancer Cell Culture

“…Because the MB controls did not produce background fluorescence, this suggests that GQDs do not interfere with or quench MB fluorescence emission. As some graphene substances exhibit distinct optical properties after being doped with various materials , it could also be that our GQD‐MB combinations might possess altered optical properties unlike those of GQD or MB alone, and these unique properties could prevent accurate assessment of cellular uptake using fluorescent spectroscopy.…”

Enhanced hydrogen storage performance of graphene nanoflakes doped with Cr atoms: a DFT study

“…The pure graphene nanoake (PGNF) consisting of 54 C atom and 18 H atoms was constructed through deleting the additional C atoms in the monolayer graphene and then saturating the hydrogen atoms at the end of C atoms in the built nanoake. [34][35][36][37] For the doped nanoake, one Gr atom was directly used to replace one of the C atoms at the center of PGNF to build the Cr-doped graphene nanoake (CrGNF). Meanwhile, the graphene nanoakes doped with two Cr atoms (2CrGNF) or three Cr atoms (3CrGNF) were also constructed in a similar way.…”

Molecular Fluorophores Self-Organize into C-Dot Seeds and Incorporate into C-Dot Structures

“…Understanding the structural features of such assemblies may help to better understand the processes of C-dot formation and origins of C-dot PL enabling rational design of C-dots with tailored properties and facilitate theoretical studies dealing with the PL properties of C-dots. [37][38][39][40][41][42] In this work, we employed classical all-atom molecular dynamics (MD) simulations in explicit solvent to analyze the self-assembly process of the molecular fluorophore IPCA and the structural features of such self-assemblies in water. We also analyzed interactions of IPCA molecules with graphitic C-dots fragments.…”