Functionalized graphene sheets as a versatile replacement for platinum in dye-sensitized solar cells

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Dye-sensitized solar cells (DSSCs) are a promising photovoltaic technology.
• Efficient counter electrodes are crucial for DSSC performance.
• Traditional platinum electrodes face limitations in cost and performance with various redox mediators.

Purpose of the Study:

• To develop and evaluate novel functionalized graphene sheet (FGS) electrodes for DSSCs.
• To compare the catalytic performance of FGS electrodes with traditional platinum electrodes.
• To investigate the impact of fabrication methods on electrode properties and DSSC efficiency.

Main Methods:

• Fabrication of FGS electrodes using ethyl cellulose as a sacrificial binder with partial thermolysis.
• Electrochemical characterization, including charge transfer resistance measurements.
• Performance testing of DSSCs with FGS electrodes using triiodide/iodide, cobalt, and sulfur redox mediators.
• Analysis of electrode structure and material properties via nitrogen adsorption and thermolysis studies.

Main Results:

• FGS electrodes exhibited lower effective charge transfer resistance (<1 Ω cm²) than traditional platinum electrodes.
• DSSC efficiencies with FGS electrodes were equal to or higher than those with platinum electrodes across three different redox mediators (I⁻, Co, S).
• High surface area is necessary but not sufficient; structural stability and electrolyte compatibility of the electrode residue are critical factors.

Conclusions:

• Ethyl cellulose-derived FGS electrodes represent a versatile and high-performing alternative to platinum counter electrodes in DSSCs.
• The fabrication method allows for tunable electrode properties crucial for efficient charge transfer and device stability.
• Understanding the interplay between binder thermolysis, electrode structure, and electrolyte interaction is key to optimizing DSSC performance.