Zinc Oxide–Titania Heterojunction-based Solid Nanospheres as Photoanodes for Electron-Trapping in Dye-Sensitized Solar Cells

Agile nanostructure architectures and smart combinations of semiconducting metal oxide materials are key features of high-performing dye-sensitized solar cells (DSSCs). Herein, we synthesize mesoporous solid nanospheres of ZnO–TiO2 with type-II heterojunction and use these as an efficient photoanode material for excellent photoconversion. These polydisperse aggregates doped with 1 %, 5 %, and 10 % of ZnO exhibit improved solar cell performance with respect to pristine TiO2 under AM 1.5 G. The 1 % ZnO doped TiO2 nanosphere possess high specific surface area (84.23 m2 g−1) as a photoanode and shows high photoconversion efficiency of about 8.07 % with ca. 18 % improvement in the photocurrent density (Jsc) compare to TiO2 nanosphere. The improved solar cell performance (Δη=40 %) of ZnO decorated TiO2 nanospheres is ascribed to type-II heterojunction of ZnO–TiO2, that reduces the electron recombination and synergistically enhances the electron mobility and charge collection capability.