Modification of reduced graphene oxide layers by electron-withdrawing/donating units on molecular dopants: Facile metal-free counter electrode electrocatalysts for dye-sensitized solar cells

摘要： Small molecules of aniline (AN) and nitrobenzene (NB) doped on reduced graphene oxide nanosheets (rGO) represent the attractive Pt-free and earth abundant counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). Scanning electron microscope and transmission electron microscope confirm a very thin layer structure with wrinkled and folded nanosheets. The binding between AN or NB and rGO is confirmed by Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). In this work, two different redox electrolytes are investigated: I?/I3? and [Co(bpy)3]3+/2+. Compared to rGO electrode-based DSSCs, the AN-rGO (1:10) and NB-rGO (1:10) electrode-based DSSCs applying I?/I3? and [Co(bpy)3]3+/2+ electrolytes show 40–50% and 30–35% increase in power conversion efficiency, respectively. Furthermore, both AN-rGO (1:10) and NB-rGO (1:10) perform stably upon electrochemical continuous test. Such excellent photoelectric performance correlates with the induced charge transfer between reduced graphene oxide and the molecules which effectively promotes the reduction and regeneration of I?/I3? and [Co(bpy)3]3+/2+ ions.