Facile synthesis of nitrogen-doped reduced graphene oxide as an efficient counter electrode for dye-sensitized solar cells

A nitrogen-doped reduced graphene oxide (N-RGO) nanosheet was synthesized by a simple hydrothermal method and characterized by X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, and scanning electrode microscopy. After being deposited as counter electrode film for dyesensitized solar cells (DSSCs), it is found that the synthesized N-RGO nanosheet has smaller charge-transfer resistance and better electrocatalytic activity towards reduction of triiodide than the reduced graphene oxide (RGO) nanosheet. Consequently, the DSSCs based on the N-RGO counter electrode achieve an energy conversion efficiency of 4.26%, which is higher than that of the RGO counter electrode (2.85%) prepared under the same conditions, and comparable to the value (5.21%) obtained with the Pt counter electrode as a reference. This N-RGO counter electrode offers the advantages of not only saving the cost of Pt itself but also simplifying the process of counter electrode preparation. Therefore, an inexpensive N-RGO nanosheet is a promising counter electrode material to replace noble metal Pt.