Graphene nanosheets@ZnO nanorods as three-dimensional high efficient counter electrodes for dye sensitized solar cells

Graphene nanosheets@ZnO nanorods as a three-dimensional high efficient counter electrode for dye sensitized solar cells is described, highlighting the ZnO nanorods as a 3D framework nanostructure for preventing the aggregations of GNs. It is demonstrated that, when the nanohybrids are used as CE materials for DSSCs, compared to their pristine GNs, the GNs@ZnO nanorod hybrids without aggregations of GNs have a significant improvement in catalytic performance toward the reduction of triiodide, which were reflected in their electrochemical properties such as high current density, narrow peak-to-peak separation (EPP) and low charge transfer resistance (RCT). The enhancement of electrochemical performance can be attributed to more active defective sites at the edges of GNs and the reduction of the restacking of GNs due to the 3D ZnO nanorod nanostructure. The DSSC with this hybrid CE exhibited energy conversion efficiency (η) of 8.12% with an open circuit voltage (VOC), short circuit photocurrent density (JSC) and fill factor (FF) of 765 mV, 21.7 mA cm−2, and 67.1%, respectively, which is comparable to that of the conventional Pt CE (8.82%).