Enhanced thermal stability of reduced graphene oxide-Silicon Schottky heterojunction solar cells via nitrogen doping

We investigated the thermal stability and electrical properties of nitrogen-doped reduced graphene oxide (NrGO)/n–type Si solar cells. A NrGO layer was used as a transparent electrode as well as an electron-hole separation layer simultaneously. The effect of doping on the carbon and nitrogen bonding configurations in NrGO was investigated using X–ray photoelectron spectroscopy (XPS). The XPS data indicate that pyridinic–N is the dominant bonding configuration. This bonding configuration leads to a reduction in the power conversion efficiency and a decrease in the short circuit current. However, on being subjected to thermal oxidation, the NrGO/n–type Si solar cells exhibit a smaller variation in series resistance compared to the undoped rGO/Si solar cells. Results of accelerated thermal tests suggest that nitrogen doping prevents re-oxidation of the reduced graphene oxide layer.