ABSTRACT
The 10 wt% TiO2 paste was prepared by mixing nanocrystalline TiO2 nanoparticles (NPs) (Degussa, P25, the average nanoparticle diameter was about 20-25 nm), Tert-butyl alcohol, and deionized water. The paste was then scraped on a transparent indium-tin-oxide (FTO) glass using doctor balding process to form TiO2 thick film. The film was annealed under air at 150 ºC for 90 min to decompose the organic compounds and then the temperature was increased up to 450 ºC for 30 min to assist the interconnection of TiO2 NPs. Later,
1 INTRODUCTION
Since the pioneering work of Grätzel and O’Regan in 1991, it opened up the possibility of practical applications as Dye-Sensitized Solar Cells (DSSCs) (B. O’Regan et al. 1991) because of low fabrication cost, good stability, and compatibility with flexible substrates. Conventional DSSCs comprises of a nanocrystalline TiO2 electrode sensitized with a ruthenium dye, a Pt-coated counter electrode consisting of a F-doped SnO2 substrate (FTO), and a liquid electrolyte with a I-/I3− redox couple (M. Grätzel et al. 2001). Due to the loss of liquid electrolyte through leakage or evaporation (P. Wang et al. 2006), the lifetime of dye-sensitized solar cells is limited, which causes problem for commercialization (D. Kuang et al. 2003). Therefore, the development of solid-state electrolyte or quasisolid electrolyte has become an important research direction (J.E. Benedetti et al. 2010). To rectify this issue and enhance durability, gel or quasi-solidstate electrolytes mixed with ionic liquids were used to improve sealing and to minimize the loss of electrolytes. Since electrolyte is an important factor affecting the conversion efficiency of DSSC, finding an optimized composition of the mixture is crucial.
