The electrolyte solutions for the DSSCs were prepared as follows: sodium iodide (3.30 g, 99.95%, Merck) and acetonitrile (30 mL) were dissolved by stirring for 15 min, prior to adding iodine (523.88 g, 99.95%, Merck) and tungstophosphoric acid hydrate (5.48 mg, H3O40PW12·xH2O, Merck). The stirring was continued for 24 h to achieve a homogeneous solution. The electrolyte solution was injected into the assembled DSSC at 50-μm spaced intervals and then sealed. The voltage and current of the DSSCs were recorded with a Keithley 2602A meter (USA) under illumination by a lamp of 1000 W/m2. The efficiency of the DSSCs was determined from the open-circuit voltage (Voc) and Jsc measurements and the calculated fill factor (FF) values. For the stability tests, the DSSCs were subjected to illumination for 100 h using lamps of 1000 W/m2 at a temperature of 50 °C.