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Graphene-based nanomaterials for solar cells 129

development of materials based on their physical properties, such as morphology, par-
ticle size, surface thickness, materials composition, and materials deposition method,
in order to increase the performance of devices. Graphene-based nanomaterials have
generated more interest among researchers as a means for improving devices’ perfor-
mance and also for the development of solar cells with improved flexibility, stability,
and lightweight solar cells [12]. In particular, graphene inorganic nanoparticle-based
nanocomposites have potential applications in these devices because of their excellent
optical, electronic, and electrical properties, and they have been applied as transparent
electrode materials in photoelectrochemical and photovoltaic devices [13].
In this chapter we briefly discuss the use of graphene and graphene-based nanomate-
2
rials and their application in different types of solar cells. Graphene is a sp -hybridized
single atomic layer of carbon arranged in honeycomb structures. [13] This precisely
two-dimensional material exhibits unique high crystal and electronic qualities and has
emerged as a promising nanomaterial for a variety of exciting applications, including
solar cells [14,15]. Graphene occurs in the plane of the CC σ bonds, which are the stron-
gest bonds. Whereas in the outer plane, it contains a π bond that provides Van der Waal
forces between the graphene layers or between the graphene and the substrate, this π
bond displays high electron mobility and is responsible for the conduction of graphene
[16,17]. The properties of graphene can vary from a single layer of atoms to a few lay-
ers, with its quantum size effect encompassing electronic, optical, mechanical, thermal,
and charge transport properties. Specifically, the electronic properties of graphene are
based largely on the arrangement and number of graphene layers. Graphene with a few
layers has an electronic structure different from that of bulk graphite [18]. Because of
these notable properties, graphene-based materials have been used as superb materials
in various energy storage and conversion devices, such as supercapacitors, solar cells,
Li-ion batteries, sensors, and so on (Fig. 7.1) [19–23].

Dye-sensitized solar cell

Perovskite solar cell
Organic photovotaic cell
Graphene based
solar cell

Schottky junction
Tandem solar cell solar cell

Fig. 7.1 Illustration of graphene-based nanostructured material in different types of
solar cells.