Silica Nanoparticle Doped Organic Ionic Plastic Crystal Electrolytes for Highly Efficient Solid-State Dye-Sensitized Solar Cells

Organic ionic plastic crystal, 1-propyl-1-methylpyrrolidinium iodide (P₁₃I), which possesses a broad plastic phase from -36 to 135 °C, was doped with silica nanoparticles (SiO₂ NPs) and 1-ethyl-3-methylimidazolium iodide (EMII), for the preparation of SiO₂/EMII/P₁₃I solid-state electrolytes for dye-sensitized solar cells (DSSCs). The thermal properties of all the electrolytes, including solid-solid phase transitions and melting temperatures, were investigated by differential scanning calorimetry (DSC). The effect of silica particles on the ionic conductivity, diffusion of I⁻/I₃⁻ redox couple in electrolytes, and photovoltaic performance for solid-state DSSCs were investigated. The fabricated solid-state DSSCs yielded a high power conversion efficiency of 5.25% under simulated air mass 1.5 solar spectrum illuminations at 50 mW cm⁻². Furthermore, the DSSCs based on SiO₂/EMII/P₁₃I solid-state electrolytes show good stability after an accelerating aging test, demonstrating potential practical applications.