Dye-sensitized solar cells based on N719 and cobalt gel electrolyte obtained through a room temperature process

• 2.15% efficiency was obtained using N719 and [Co(bpy)3]2+/3+.
• PMMA-based cobalt gel electrolyte was obtained through a room temperature process.
• Quasi-solid device retained 70% of the efficiency of the liquid-based reference.
• Quasi-solid device showed a substantial stability after 120 days.

Quasi-solid dye-sensitized solar cells were obtained by coupling N719 dye with a cobalt gel electrolyte. Firstly, the compatibility of the liquid [Co(bpy)3]3+/2+ redox mediator with N719 was improved by modifying the surface of sensitized photoanode, which resulted in an increase in efficiency of over 100%. Most importantly, a novel room-temperature route for producing a [Co(bpy)3]3+/2+-PMMA gel electrolyte was introduced for the first time. The formation of the gel phase was demonstrated by rheological analyses and the electrolyte was subjected to an extensive electrochemical characterization. The derived quasi-solid devices attained 70% of the efficiency of the liquid ones, and showed a degradation of only 15% after 120 days, which proved the high stability of the developed system.