Hydrothermal synthesis of mesoporous TiO2-SiO2 core-shell composites for dye-sensitized solar cells

• TiO2-SiO2 core-shell composites were synthesized by a facile sol-gel method.
• The thickness of SiO2 shell is controllable.
• SiO2 addition retarded the anatase-rutile transformation.
• The recombination was inhibited by SiO2 shell.
• Solar cell performance was much improved by SiO2 loading.

It is challenging to utilize TiO2-based composites with high specific surface area to improve dye-sensitized solar cells (DSSCs) performance. Herein, we report efficient TiO2-SiO2 core-shell composites for DSSCs by optimizing the microstructure and crystalline structure. Mesoporous TiO2-SiO2 core-shell composites were synthesized by hydrolysis of TiOCl2 and Si(C2H5O)4 under hydrothermal condition. The shell thickness can be tuned through adjustment of the SiO2 addition content. Rutile phase of TiO2 formed without SiO2 addition, while anatase phase of TiO2 was stabilized by SiO2 loading. By addition of SiO2, the crystallite size decreased from 29 nm of rutile to 15 nm of anatase, and the specific surface area increased from 23 m2/g to 150 m2/g. The best transfer efficiency (5.9%) was obtained in TiO2-SiO2(0.10), which is much higher than that of commercial TiO2 powder (P25).

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