Synthesis of highly-ordered TiO₂ through CO₂ supercritical extraction for dye-sensitized solar cell application

Dye-sensitized solar cell (DSSC) is one of the very promising alternative renewable energy sources to anticipate the diminishing in the fossil fuel reserves in the next few decades and to make use of the abundance of intensive sunlight energy in tropical countries like Indonesia. TiO₂ nanoparticles have been used as the photo electrode in DSSC because of its high surface area and allow the adsorption of a large number of dye molecules. In the present study, TiO₂ aerogel have been synthesized via sol-gel process with water to inorganic precursor ratio (R_w) of 2.00, followed with subsequent drying by CO₂ supercritical extraction (SCE). As comparison, the TiO₂ xerogel was also prepared by conventional drying and annealing. Both types of gels were subjected to conventional and multi-step annealing. The resulting nanoparticles in aerogel and xerogel have a band-gap energy of 3.10 and 3.04 eV, respectively. The open circuit voltage (V_oc) measurement reveals that the DSSC fabricated with aerogel provided a higher voltage (21,40 mV) than xerogel (1,10 mV).