Preparation of Graphene

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) as well 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.