Design and Simulation of Finger-Shape GrapheneSilicon Schottky Junction Solar Cell based on Asymmetrical Metallization to Enhance the Efficiency

By the use of graphene in graphene/silicon schottky junction solar cell, we can benefit from the unique characteristics of graphene not only as an electrode but also as an absorbing material. In this paper we have proposed two new structures for the solar cell based on graphene/silicon junction. In these new structures, it is possible to collect the optical carriers generated in graphene as well as silicon and this is the reason of enhancement in the efficiency of the solar cell. The intrinsic electric field made by the schottky barrier between graphene and silicon in graphene/silicon schottky junction, separates the electron-hole pairs generated in silicon under radiation and cause the photo current in external circuit. In our new structures, we have benefited from graphene as an absorber by producing an extra electric field on the surface of graphene layer. The effect of surface metallization on band diagram of graphene will make this electric field. Conventional metallization of graphene solar cells has window-shape structure. In this structure, graphene is used just as a semitransparent electrode. The two proposed metallizations have asymmetrical and interdigitated finger shapes. The simulation is done by TCAD Silvaco software and declares that in conventional graphene/silicon schottky junction solar cell with window like metallization, the PCE is 2. 7% whereas in solar cell with asymmetrical metallization by two different work functions, the PCE reaches to 3. 5%. By the use of interdigitated finger structure metallization, the PCE would increase to 4. 3%.