Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optical spectrum of bottom-up graphene nanoribbons: towards efficient
  atom-thick excitonic solar cells   Recently, atomically well-defined cove-shaped graphene nanoribbons have been
obtained using bottom-up synthesis. These nanoribbons have an optical gap in
the visible range of the spectrum which make them candidates for donor
materials in photovoltaic devices. From the atomistic point of view, their
electronic and optical properties are not clearly understood. Therefore, in
this work we carry out ab-initio density functional theory calculations combine
with many-body perturbation formalism to study their electronic and optical
properties. Through the comparison with experimental measurements, we show that
an accurate description of the nanoribbon's optical properties requires the
inclusion of electron-hole correlation effects. The energy, binding energy and
the corresponding excitonic transitions involved are analyzed. We found that in
contrast to zigzag graphene nanoribbons, the excitonic peaks in the absorption
spectrum are a consequence of a group of transitions involving the first and
second conduction and valence bands. Finally, we estimate some relevant optical
properties that strengthen the potential of these nanoribbons for acting as a
donor materials in photovoltaic.

25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
1
The categories of this paper are: cs
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
29
The categories of this paper are: funct-an