Optically transparent cathode for dye-sensitized solar cells based on graphene nanoplatelets

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Platinum is the standard cathode material in dye-sensitized solar cells (DSCs).
• Developing cost-effective and efficient alternatives to platinum is crucial for commercializing DSC technology.
• Graphene nanoplatelets offer unique electronic and catalytic properties for energy applications.

Purpose of the Study:

• To investigate the electrocatalytic activity of graphene nanoplatelets (GNPs) as a cathode material for DSCs.
• To evaluate the performance of GNPs in different electrolyte media, including ionic liquids.
• To assess the potential of GNPs as a substitute for platinum and FTO in DSCs.

Main Methods:

• Fabrication of optically transparent GNP thin films on F-doped SnO(2) (FTO) substrates.
• Electrochemical characterization using electrochemical impedance spectroscopy (EIS) to determine charge-transfer resistance (R(CT)).
• Assembly and testing of DSCs with GNP cathodes under simulated solar illumination.

Main Results:

• GNP films exhibited high electrocatalytic activity for the I(3)(-)/I(-) redox couple, with significantly lower R(CT) in ionic liquid electrolytes compared to traditional organic electrolytes.
• Electrocatalytic activity correlated with the concentration of active sites (edge defects and oxidic groups) on the GNPs.
• DSCs with GNP cathodes demonstrated efficient photocurrent collection but require further reduction in R(CT) for improved performance near open-circuit potential.

Conclusions:

• Graphene nanoplatelets are a strong candidate for replacing platinum and FTO in DSC cathodes.
• The performance of GNP cathodes is dependent on the electrolyte composition and the intrinsic properties of the graphene material.
• Further optimization of GNP materials and device architecture could lead to highly efficient and cost-effective DSCs.