An organic ionic plastic crystal, 1-ethyl-1-methylpyrrolidinium bis(trifluoromethanesulfonyl) imide (P₁₂TFSI), was synthesized and doped with a room temperature ionic liquid, 1-propyl-3-methylimidazolium iodide (PMII). The prepared PMII/P₁₂TFSI solid-state electrolytes were employed for dye-sensitized solar cells (DSSCs), without using any volatile organic solvent. The fabricated solid-state DSSCs yielded a power conversion efficiency of 5.12% under simulated air mass 1.5 solar spectrum illuminations at 50 mW cm⁻². The superior long-term stability of the fabricated solid-state DSSCs indicated that the synthesized PMII/P₁₂TFSI solid-state electrolytes could overcome the drawbacks of cells containing volatile solvents.