Efficient copper mediators based on bulky asymmetric phenanthrolines for DSSCs

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Dye-sensitized solar cells (DSSCs) require efficient electron mediators to replace the conventional iodide/triiodide (I3(-)/I(-)) redox couple.
• Copper(I)-phenanthroline complexes are explored as potential alternatives due to their tunable redox properties.

Purpose of the Study:

• To synthesize and characterize novel copper(I)-phenanthroline complexes for DSSC applications.
• To evaluate the performance of these complexes as electron mediators, focusing on dye regeneration kinetics and dark current.

Main Methods:

• Facile synthesis of a series of copper(I)-phenanthroline complexes.
• Preparation of a novel complex, [Cu(2-mesityl-4,7-dimethyl-1,10-phenanthroline)2]PF6 (3), featuring bulky mesityl groups.
• Fabrication and testing of DSSCs using a dual-component electrolyte with complex (3) and a ruthenium-based sensitizer.

Main Results:

• Complex (3) demonstrated superior dye regeneration kinetics and reduced dark current compared to simpler copper(I) complexes and the I3(-)/I(-) system.
• A DSSC utilizing a dual-component electrolyte with complex (3) achieved a photocurrent density (Jsc) of 4.0 mA cm(-2), comparable to the I3(-)/I(-) system (3.8 mA cm(-2)).

Conclusions:

• Bulky substituents on phenanthroline ligands enhance the protective effect around the copper center, improving mediator performance.
• Copper(I)-phenanthroline complexes, particularly complex (3) in a dual-component electrolyte, show significant promise for efficient and stable dye-sensitized solar cells.