Fabrication of Solid-State Dye-Sensitized Solar Cells by Controlled Evaporation of Solvents for Creation of Facile Charge Transport Pathway

Solid-state dye-sensitized solar cells (ss-DSSCs) based on MK-2 dye-sensitized TiO2 photoanode and the most commonly used I-/I(3)(- )redox electrolyte are successfully fabricated by the simple method of solidification of the injected liquid electrolyte under slow solvent evaporation. The use of the ionic liquid, which is solid at room temperature, and slow evaporation of solvent at low temperature is a key step for solidification toward the fabrication of ss-DSSCs. It has been demonstrated that ss-DSSCs thus fabricated not only retain about 80% of photoconversion efficiency (PCE) as compared to their liquid-state DSSCs counterpart but also maintain the device stability for more than 1000 h. PCE of the ss-DSSCs is found to increase as a function of the increasing concentration of the ionic liquid used for electrolyte preparation. In the case of ss-DSSCs with the ionic liquid concentration of 1.2 m, there is a good balance between PCE and durability leading to not only retention of about 70% of PCE as compared to its liquid-state DSSCs counterparts but also maintaining the stability of the solar cell for more than 1000 h stored at room temperature.