Effect of characteristic properties of graphene oxide on reduced graphene oxide/Si schottky diodes performance

We investigated the effect of the size of graphene oxide (GO) sheets made with two different types of GO solution on the performance of Si-based solar cells. Large-sized reduced GO (rGO) with an in-plane crystalline diameter of 3.42 nm has smaller defect sites and thus the Si/rGO Schottky junction solar cell shows a lower leakage current than the solar cell with small-sized rGO (i.e. an in-plane crystalline diameter of 3.03 nm). Enhanced open-circuit voltage (V_oc) and improved short-circuit current (J_sc) are observed for the solar cell with large-sized rGO due to the increased work function and Schottky barrier height at the Si and rGO junction. In other words, an increased built-in potential and a wider depletion region of the solar cell with large-sized rGO contribute to the increased carrier absorption and generation. These findings indicate that (i) rGO acts as a good transparent conducting layer and hole-transporting layer, and (ii) the control of rGO size in Si/rGO Schottky junction solar cell is important to improve the performance.