1 Introduction
Graphene is a very special material, since it
has the advantage of being both conducting
and transparent. The transparency of a material
normally depends on its electronic properties
and requires a band gap. Under normal
conditions transparency and conductivity
exclude each other, except for a few compounds
like indium tin oxide (ITO). However,
in contrast to ITO, graphene is also flexible
and capable of withstanding high stress.
Therefore it is very attractive for the application
of flexible electronic devices, e.g. touch
screens [1]. Accordingly, there are a lot of efforts
in order to prepare graphene easyly with
the required properties.
The methods described in this review are
evaluated on the bases of different requirements:
On the purity of the graphene, which
is defined by the lack of intrinsic defects,
(Quality) aswell as on the size of the obtained
flakes or layers (Size). Another aspect is the
amount of graphene which can be produced
simultaneously (Amount) or the complexity
such as the requirement of labour or the need
for specially designed machines (Complex.).
One last attribute is the controllability of the
method in order to achieve reproducible results
(Control.).
This review is organized as follows: In Sec.
2 the exfoliation methods are presented and
discussed. Following that another type of
preparation, the growth of graphene, will be
introduced in Sec. 3. Concluding, the different
methods will be compared in Sec. 4.