Graphene-embedded 3D TiO sub(2) inverse opal electrodes for highly efficient dye-sensitized solar cells: morphological characteristics and photocurrent enhancement

We demonstrated the preparation of graphene-embedded 3D inverse opal electrodes for use in DSSCs. The graphene was incorporated locally into the top layers of the inverse opal structures and was embedded into the TiO sub(2) matrix viapost-treatment of the TiO sub(2) precursors. DSSCs comprising the bare and 1-5 wt% graphene-incorporated TiO sub(2) inverse opal electrodes were compared. We observed that the local arrangement of graphene sheets effectively enhanced electron transport without significantly reducing light harvesting by the dye molecules. A high efficiency of 7.5% was achieved in DSSCs prepared with the 3 wt% graphene-incorporated TiO sub(2) inverse opal electrodes, constituting a 50% increase over the efficiencies of DSSCs prepared without graphene. The increase in efficiency was mainly attributed to an increase in J sub(SC), as determined by the photovoltaic parameters and the electrochemical impedance spectroscopy analysis.