Oxygenated-graphene-enabled recombination barrier layer for high performance dye-sensitized solar cell

Wide-bandgap multilayer oxygenated graphene (MLOG) is used as the recombination barrier layer (RBL) in dye-sensitized solar cell (DSSC). The MLOG is derived from multilayer graphene synthesized by chemical vapor deposition (CVD) and oxygenated with high density/low power oxygen plasma. We observe 19% improvement in photoconversion efficiency of the DSSC with MLOG RBL, as compared with DSSC without RBL. Lifetime of photo-injected electrons at the conduction band of TiO2 nanoparticle electrode is increased due to the presence of MLOG. This is attributed to effective collection of electrons at the transparent conductor electrode by suppressing interfacial-recombination via TiO2 surface states. The control over dark current of the DSSC is also significantly enhanced with MLOG as compared with that without RBL as the direct result of improved interfacial quality of the TiO2/dye/electrolyte structure.