Graphene-on-Silicon solar cells with graphite contacts

This paper proposes an innovative technology for top contacting graphene-on-silicon Schottky solar cells, making use of graphite glue instead of the commonly used Ti/Au bilayer. Current-Voltage light characterization allow immediately to appreciate the advantage of the innovative contact evidencing the highest FF ever obtained in a graphene/Si solar cell with pristine (undoped) graphene and without graphene/silicon interlayer. To better understand the electrical behavior of our devices, solar cells realized either with gold contacts or with graphite contacts are compared by means of the impedance spectroscopy analysis too. It is shown that gold contacts give rise to strongly distorted impedance spectra and that such a distortion is due to the contact resistance. Conversely, graphite contacts result in extremely regular impedance spectra, as expected for ohmic behaving contacts.