Butyronitrile-based electrolyte for dye-sensitized solar cells.

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Dye-sensitized solar cells (DSSCs) require stable and efficient electrolytes for commercial viability.
• Low volatility and controlled energetics of charge transport are critical for DSSC performance and longevity.

Purpose of the Study:

• To develop a novel, low-volatility electrolyte for DSSCs based on a butyronitrile solvent.
• To investigate the effect of sodium iodide (NaI) incorporation on trap state energetics and cell stability.
• To achieve high power conversion efficiency (PCE) and long-term operational stability in DSSCs.

Main Methods:

• Formulation of a new electrolyte using butyronitrile solvent and NaI.
• Characterization of electrolyte properties, including volatility and compatibility.
• Fabrication and testing of DSSCs using the new electrolyte and a thiophene-based C106 sensitizer.
• Evaluation of cell performance under varying light intensities and accelerated aging conditions (IEC 61646 protocol).

Main Results:

• The butyronitrile-based electrolyte demonstrated low volatility and passed the IEC 61646 stability test protocol.
• Incorporation of NaI effectively controlled trap state energetics in a sub-Nernstian manner without compromising stability.
• A champion DSSC achieved 10.2% PCE under 51.2 mW·cm⁻² and 10.0% PCE under 100 mW·cm⁻².
• The cells retained over 95% of their initial PCE after 1000 hours of light-soaking at 60 °C, with a PCE of 9.1%.

Conclusions:

• The developed butyronitrile-based electrolyte offers a promising solution for stable and efficient DSSCs.
• NaI incorporation is a viable strategy for optimizing charge carrier dynamics and enhancing DSSC operational stability.
• The combination of the novel electrolyte and C106 sensitizer yields high-performance DSSCs meeting stringent stability requirements.