Mesoporous TiO2 aggregate photoanode with high specific surface area and strong light scattering for dye-sensitized solar cells

Phase-pure anatase TiO2 nanocrystallite aggregates synthesized by a continuous supercritical fluid process have been first used for fabricating mesoporous photoanodes of dye-sensitized solar cells (DSCs). Due to the small size (11 nm) of the TiO2 nanocrystallites in the aggregates, the mesoporous photoanode provides a high specific surface area, 80 m2/g, which ensures high dye loading. At the same time, the submicrometer-sized aggregates endow the mesoporous photoanode with strong light scattering effect. Therefore, the light harvesting efficiency of the photoanode is increased. With an improved short-circuit current density, a high overall power conversion efficiency of 8.65% (100 mW/cm2, AM 1.5) is achieved without additional scattering layers, 12% enhanced compared with the DSCs fabricated from commercial Degussa P25 with exactly the same procedures. In addition, this supercritical fluid process is scalable and rapid (less than one minute) for TiO2 aggregates synthesis, which will push the commercialization of DSCs in the future.