Organic ionic plastic crystal, 1-ethyl-1-methyl pyrrolidinium iodide (P12I), is employed as the solid-state electrolytes for dye-sensitized solar cells. The fabricated solid-state devices show an overall power conversion effi ciency of similar to 5.8% under AM 1.5 radiation (50 mW/cm(2)) and excellent long-term stability at 80 degrees C.