Graphene nanosheets inserted by silver nanoparticles as zero-dimensional nanospacers for dye sensitized solar cells

Abstract

Three-dimensional Ag nanoparticle/GNs (Ag/GNs) hybrids as highly efficient counter electrode (CE) materials for dye sensitized solar cells (DSSCs) is described, highlighting the Ag nanoparticles as zero-dimensional nanospacers inserting into GNs to lift the interspacing layer between individual GNs. It is demonstrated that, when the hybrids are used as CE materials for DSSCs, compared to their pure GNs, Ag/GNs hybrids without agglomerates have a significant improvement 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 the increased electrode conductivity, an extended interlayer distance and the reduction of the restacking of graphene sheets due to the insertion of metallic Ag nanoparticles into GNs. The DSSC with this hybrid CE exhibited an energy conversion efficiency (η) of 7.72% with an open circuit voltage (VOC), short circuit photocurrent density (JSC), and fill factor (FF) of 732 mV, 14.67 mA cm(-2), and 71.8%, respectively.

In-situ Grown Hybrid Nanocarbon Composite for Dye Sensitized Solar Cells

“…The peak current density and the peak-to-peak separation (Epp), which is negatively correlated with the standard electrochemical rate constant of a redox reaction, are two important parameters for comparing catalytic activities of different CEs [14,15]. Although the electrode with hybrid CNTs/ graphene film has lower peak cathodic current density (1.12 mA cm À2 ) than that of Pt CE and a larger overpotential is required in the hybrid CNTs/graphene CE to drive the reaction [55], it shows a higher peak cathodic current density than that (1.06 mA cm À2 ) of pure CNTs CE reported by K.C.…”

“…Among these carbon materials, particularly, one dimensional (1D) carbon nanotubes (CNTs) and two dimensional (2D) graphene attract considerable interest for electrocatalytic applications in DSSCs due to their high electrochemical stability, low resistivity and high catalytic activity [3][4][5][11][12][13][14][15][16]. Besides, compared with the Pt catalytic layer, these carbon materials with high optically transparency could be used as the transparent CE for DSSCs.…”

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

“…3,31 In this work, the laser energy was 250 mJ and the laser repetition rate was 3 Hz. The graphene content of the mixture was calculated from the feeding weights of the components.…”

“…Recently, lattice defects such as defective sites at the edges of graphene are considered as main electrocatalytic active sites for the reduction of I 3 − . 12,13,16 Unfortunately, due to the strong π−π interaction between the large basal planes of graphene, the edges of graphene always form the cluster, 3,[17][18][19] which significantly lose their high surface area advantage as a two-dimensional nanomaterial, intrinsic chemical and physical properties, leading to reduce the amount of active defective sites accessibility for the reduction of I 3 − and further limits the conversion efficiency of DSSCs. As a result, the aggregated GNs behave differently than particulate GNs due to the loss of active defective sites.…”

“…The CE plays a key role in regulating the DSSC performance by catalyzing the reduction of the iodide-triiodide redox species used as a mediator to regenerate the sensitizer after electron injection. [1][2][3][4] Therefore, the ideal CE material should possess a low sheet resistance, high reduction catalytic activity, good chemical stability, and low production cost. 5,6 Because of its excellent electrocatalytic activity for the iodine reduction, high conductivity and good chemical stability, platinum (Pt) has been widely used as a CE in DSSCs.…”