Graphene Nanoplatelets–Nickel Nanoparticles Hybrid Counter Electrodes for Low-Cost and Efficient Dye-Sensitized Solar Cells

Abstract

Reducing the cost of dye-sensitized solar cells (DSSCs) by replacing the expensive platinum (Pt) counter electrode (CE) with low-cost and earth-abundant materials without sacrificing their power conversion efficiency (PCE) is a topic of high interest. Herein, we prepared graphene nanoplatelets/nickel nanoparticles (GnPs/NiNPs) hybrid as a CE for DSSCs by electrochemical deposition of NiNPs onto fluorine-doped tin oxide (FTO) followed by spin coating of GnPs onto NiNPs/FTO electrodes. The optimal GnPs/NiNPs-CE with homogeneously distributed NiNPs with well-defined crystallinity exhibited excellent catalytic activity toward the I−/I3 − redox mediator with low charge transfer resistance at the electrode∣electrolyte interface. The DSSCs with an optimized GnPs/NiNPs-CE electrode exhibited a substantial improvement in efficiency to 7.24%, which is similar to the PCE of the cells with Pt-CE (ca. 7.99%). The GnPs/NiNPs-CE is a promising replacement for the expensive Pt used in DSSCs.

Low-Cost and Efficient Nickel Nitroprusside/Graphene Nanohybrid Electrocatalysts as Counter Electrodes for Dye-Sensitized Solar Cells

“…Platinum (Pt) is widely used as a conventional CE material in DSSCs due to its superior catalytic activity toward the redox reaction of conventional I − /I 3 − electrolyte and high electrical conductivity (9.43 × 10 6 S/m) [ 9 ]. However, the high cost of Pt (4.6 USD/m 2 for a 5 nm-thick Pt film) hinders its large-scale application in DSSCs [ 10 , 11 ].…”

“…For the replacement of Pt-CE, numerous studies have demonstrated, using, for example, carbonaceous materials (e.g., graphene, carbon nanotubes, active carbon, graphite, carbon black) [ 12 ], conducting polymers (CPs) (e.g., polyaniline, polypyrrole, and poly(3,4-ethylene dioxythiophene) (PEDOT: PSS)) [ 13 ], transition metal compounds (e.g., carbides, nitrides, oxides) [ 14 ], and various hybrids or composites materials [ 15 ], which are about 10 to 10,000 times cheaper than that of Pt-CE [ 10 ]. Among them, nanostructures of metallic Ni and its compounds (e.g., oxides, sulfides, ternary sulfides, phosphides) are potentially suitable CE materials because of their decent corrosion resistance to the I − /I 3 − redox mediator and low cost [ 11 , 16 , 17 , 18 , 19 , 20 ]. However, their electrocatalytic activity for the redox reaction of I − /I 3 − and electrical conductivity is inadequate for developing high-performance DSSCs [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”

“…However, their electrocatalytic activity for the redox reaction of I − /I 3 − and electrical conductivity is inadequate for developing high-performance DSSCs [ 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Therefore, attempts were made to enhance the conductivity as well as the overall catalytic activity by preparing Ni nanostructure and its compounds-based composites or hybrid CEs using CPs [ 17 , 20 , 23 ], graphene [ 11 , 19 , 22 , 24 ], and CPs-graphene [ 25 ]. These reported Ni and its compounds-based composites/hybrid CEs outperformed the PV performance of an I − /I 3 − redox mediator-based DSSCs compared to their single component-based CEs.…”

“…Graphene has attracted broad attention for preparing metallic Ni and its compounds-based composites/hybrids-CEs [ 11 , 19 , 22 , 24 , 26 , 27 , 28 , 29 , 30 ]. This is due to the low cost, natural abundance, nontoxicity, and high specific surface area of graphene [ 6 ].…”

“…This is due to the low cost, natural abundance, nontoxicity, and high specific surface area of graphene [ 6 ]. The excellent electrical conductivity of graphene, arising from the confinement of electrons in two dimensions, is induced to increase the net electrical conductivity of the composites or hybrids [ 11 ]. Additionally, graphene can synergistically enhance the overall electrocatalytic activity of the composites for the redox reaction of I − /I 3 − .…”