From
the moment atomic precision control of the growth process
of graphene was achieved, more elaborated carbon allotropes were proposed
opening new channels for flat optoelectronics at the nanoscale. A
special type of this material presenting a V-shape (or “kinked”
pattern) was recently synthesized and named chevron-graphene nanoribbons
(C-GNRs). To realize the reach of C-GNRs in developing new applications,
the formation and transport of charge carriers in their lattices should
be primarily understood. Here, we investigate the static and dynamical
properties of quasiparticles in C-GNRs. We study the effects of electron–phonon
coupling and doping on the system. We also determine the kind of charge
carriers present in C-GNR. Two distinct physical pictures for the
charge transport were obtained: a delocalized regime of conduction
and a regime mediated by charge carriers. These transport regimes
are highly dependent on the doping concentration. Importantly, similarities
in charge carrier terminal velocities were observed among C-GNRs and
standard armchair graphene nanoribbons, which originate from their
comparable charge localization profiles that yield quasiparticles
with equivalent effective masses.
Graphene nanoribbons (GNRs) are two-dimensional structures with a rich variety of electronic properties that derive from their semiconducting band gaps. In these materials, charge transport can occur via a hopping process mediated by carriers formed by self-interacting states between the excess charge and local lattice deformations. Here, we use a two-dimensional tight-binding approach to reveal the formation of bipolarons in GNRs. Our results show that the formed bipolarons are dynamically stable even for high electric field strengths when it comes to GNRs. Remarkably, the bipolaron dynamics can occur in acoustic and optical regimes concerning its saturation velocity. The phase transition between these two regimes takes place for a critical field strength in which the bipolaron moves roughly with the speed of sound in the material.
Two-dimensional C 60 crystals are treated with a Holstein− Peierls model that takes into account both intra-and intermolecular vibrational modes to describe charge transport. By virtue of this procedure, we obtained the set of values for intra-and intermolecular electron−phonon coupling that makes it possible to study stationary properties of polarons as well as to investigate the transport regime of the charge carriers. This is carried out by considering the presence of anisotropy of electronic terms and effects because of the application of external electric fields. We have mapped the regimes in which polarons of different nature each endowing the system with different propertiesare observed.
Graphene nanoribbons (GNRs) are promising quasi-one-dimensional materials with various technological applications. Recently, methods that allowed for the control of GNR’s topology have been developed, resulting in connected nanoribbons composed of two distinct armchair GNR families. Here, we employed an extended version of the Su-Schrieffer-Heeger model to study the morphological and electronic properties of these novel GNRs. Results demonstrated that charge injection leads to the formation of polarons that localize strictly in the 9-AGNRs segments of the system. Its mobility is highly impaired by the system’s topology. The polaron displaces through hopping between 9-AGNR portions of the system, suggesting this mechanism for charge transport in this material.
Recently, a new two-dimensional carbon allotrope, named biphenylene network (BPN) was experimentally realized. The BPN structure is composed of four-, six-, and eight-membered rings of sp$^2$-hybridized carbon atoms. In this...
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