Iodine-Pseudohalogen Ionic Liquid-Based Electrolytes for Quasi-Solid-State Dye-Sensitized Solar Cells.

Area of Science:

• Materials Science
• Electrochemistry
• Renewable Energy

Background:

• Ionic liquids (ILs) are promising electrolytes for dye-sensitized solar cells (DSSCs).
• Optimizing electrolyte composition is crucial for enhancing DSSC performance and stability.
• Quasi-solid-state DSSCs (qssDSSCs) offer advantages over liquid-electrolyte counterparts.

Purpose of the Study:

• To synthesize and characterize novel imidazolium-based ionic liquids with iodide (I-) or selenocyanate (SeCN-) counteranions.
• To evaluate these ILs as electrolytes in qssDSSCs, optimizing with additives like 4-tert-butylpyridine (4tbpy) and guanidinium thiocyanate (GuSCN).
• To investigate the impact of iodine-pseudohalogen electrolytes on device performance, particularly open-circuit voltage and energy conversion efficiency.

Main Methods:

• Synthesis of symmetrically alkyl-substituted imidazolium-based ionic liquids.
• Physicochemical characterization using spectroscopy and electrochemistry.
• Fabrication and testing of quasi-solid-state dye-sensitized solar cells (qssDSSCs) with optimized electrolytes.

Main Results:

• Ionic liquids with I- or SeCN- counteranions were successfully synthesized.
• Electrolytes containing a mixture of I2 and (SeCN)2 enhanced the open-circuit voltage by up to 70 mV.
• The iodine-pseudohalogen electrolyte improved overall solar energy conversion efficiency by 70% compared to iodine-based electrolytes.
• Devices demonstrated a stable efficiency of 7-8% over 1000 hours under operational conditions.

Conclusions:

• Novel ionic liquids with iodide and selenocyanate counteranions are effective electrolytes for qssDSSCs.
• Iodine-pseudohalogen electrolytes offer a superior balance of dye regeneration and hole transport.
• These advanced electrolytes significantly enhance the efficiency and long-term stability of qssDSSCs.