First-principles study of multicontrol graphene doping using light-switching molecules

Abstract

The high carrier mobility in graphene promises its utility in electronics applications. Azobenzene is a widely studied organic molecule for switchable optoelectronic devices that can be synthesized with a wide variety of ligands and deposited on graphene. Using first-principles calculations, we investigate graphene doping by physisorbed azobenzene molecules with various electron-donating and −accepting ligands. We confirm previous experimental results that demonstrate greater pdoping of graphene for the trans compared to cis configuration when using a SO3 electron-accepting ligand, however we find that NO2 ligands maximize the p-doping difference between isomers. We also examine how these doping effects change when the graphene monolayer is supported on a silica substrate. We then extend these findings by examining the doping effects of an applied electrical bias and mechanical strain to the graphene, which lead to changes in doping for both the trans and cis isomers. These results demonstrate a new type of multi-control device combining light, electric field, and strain to change carrier concentration in graphene.

First-principles study of magnetism and electric field effects in 2D systems

“…66 We further applied azobenzene molecules to modulate the interaction between the two nanoparticles and studied the interaction with graphene surfaces in the two configurations. 67,68 These studies demonstrated that one can use the configuration change to manipulate physical properties of a system. Simulations of the graphene | azobenzene | graphene vertical junction is therefore a natural extension of our long-standing interest in the added technique for gating the system.…”

Clar's goblet on graphene: field modulated charge transfer in a hydrocarbon heterostructure

“…Graphene has been valued as a novel thin film semiconductor due to its special electronic properties resulting from the Dirac cone. Shifting of the Dirac cone through charge transfer has been observed in the adsoption of magnetic molecules on monolayer graphene 9,10 . Adsorption of certain adatom dimers induces spin-dependence in graphene, leading to half-metalicity in the case of iron 11 .…”

“…Adsorption of certain adatom dimers induces spin-dependence in graphene, leading to half-metalicity in the case of iron 11 . Adding ligands to metal molecules allows for varying levels of hole doping, shifting the cone above the Fermi energy 10,[12][13][14][15] . The adsorption geometry is of note in the context of charge transfer, as seen in the adsorption of azobenzene; an external gating field induces differing charge doping between the isomers of this photoswitching molecule and graphene 10 .…”

“…Adding ligands to metal molecules allows for varying levels of hole doping, shifting the cone above the Fermi energy 10,[12][13][14][15] . The adsorption geometry is of note in the context of charge transfer, as seen in the adsorption of azobenzene; an external gating field induces differing charge doping between the isomers of this photoswitching molecule and graphene 10 . Gold clusters display a similar correlation, with Au 6 (commensurate packing with the graphene substrate) being physisorbed and yielding little charge transfer as opposed to Au 3 (vertical adsorption) 12 .…”

Computational chemistry for graphene-based energy applications: progress and challenges

“…While graphene films exposed to air will show this effect, the charge carrier concentration can be increased by further chemical doping, which will reduce the resistance of the film further. 118 The doping of graphene films by substrates, 48,[125][126][127][128][129][130][131][132][133] noncovalently adsorbed molecules, 47,122,[134][135][136][137][138] or the insertion of B/N atoms into the graphene film [139][140][141][142] can either induce charge transfer from the graphene, p or hole doping, or to the graphene, electron or n, doping. Manipulation of bandgap properties is central to advancing developments in photovoltaics.…”