Organic ionic plastic crystal, 1-propyl-1-methylpyrrolidinium iodide (P
13I), which possesses a broad plastic phase from -36 °C to 135 °C, was doped with silica nanoparticles and 1-ethyl-3-methylimidazolium iodide (EMII) to prepare the SiO
2/EMII/P
13I solid-state electrolytes, and applied to 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
−/I
3− 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 maintains 92 % of the initial efficiency after 1000 h test, demonstrating excellent long-term stability.
