Graphene for solar cells

In recent years, solar energy has received extensive attention as a viable source of green energy. The variety of solar cells has increased considerably, from crystalline silicon solar cells, amorphous silicon thin-film solar cells to newer forms such as dye-sensitized solar cells (DSSCs) and organic solar cells. The specific electrical and optical properties are requisite to the material used in solar cells. In 2004, Geim et al. prepared graphene by the scotch tape method and sparked the unprecedented attention of graphene materials. Graphene, a single-atomic-layer material, has excellent intrinsic properties, such as large surface area (2630 m2/g), outstanding carrier mobility of 20,000 cm2/(V·s), large Young’s modulus 82(1.0 TPa), excellent thermal conductivity of 5000 W/(m·k), and high light transmittance (97.7%) [1,2]. These unique properties, along with exceptional electrical conductivity and mechanical flexibility, render graphene and its derivatives as potential candidates in the field of solar cells. To date, lots of impressive results have been reported, where graphene was used as electrodes, i.e., transparent cathodes as well as non-transparent anodes [3-5]. Graphene has also been used in DSSCs and organic photovoltaic cells (OPV), as light-harvesting material electron transport layer, hole transport layer (HTL), and interfacial layer in the tandem configuration [6-9]. In this chapter, we will review the application of graphene in solar cells.