Rapid Room-Temperature Synthesis of Mesoporous TiO₂ Sub-Microspheres and Their Enhanced Light Harvesting in Dye-Sensitized Solar Cells

• Main Authors: Mohammad Alduraibi, Mahmoud Hezam, Bader Al-Ruhaimi, Ahmed Mohamed El-Toni, Ahmad Algarni, M. Abdel-Rahman, Wang Qing, Abdullah Aldwayyan
• Format: Article
• Language: English
• Published: MDPI AG 2020-02-01
• Series: Nanomaterials
• Subjects: titanium dioxide; dye-sensitized solar cells; anatase; surfactant; ctab; light scattering
• Online Access: https://www.mdpi.com/2079-4991/10/3/413

Submicron sized mesoporous spheres of TiO₂ have been a potential alternative to overcome the light scattering limitations of TiO₂ nanoparticles in dye-sensitized solar cells (DSSCs). Currently available methods for the growth of mesoporous TiO₂ sub-microspheres involve long and relatively high temperature multi-stage protocols. In this work, TiO₂ mesoporous sub-microspheres composed of ~5 nm anatase nanocrystallites were successfully synthesized using a rapid one-pot room-temperature CTAB-based solvothermal synthesis. X-Ray Diffraction (XRD) showed that the grown structures have pure anatase phase. Transmission electron microscopy (TEM) revealed that by reducing the surfactant/precursor concentration ratio, the morphology could be tuned from monodispersed nanoparticles into sub-micron sized mesoporous beads with controllable sizes (50−200 nm) and with good monodispersity as well. The growth mechanism is explained in terms of the competition between homogeneous nucleation/growth events versus surface energy induced agglomeration in a non-micelle CTAB-based soft templating environment. Further, dye-sensitized solar cells (DSSCs) were fabricated using the synthesized samples and characterized for their current-voltage characteristics. Interestingly, the DSSC prepared with 200 nm TiO₂ sub-microspheres, with reduced surface area, has shown close efficiency (5.65%) to that of DSSC based on monodispersed 20 nm nanoparticles (5.79%). The results show that light scattering caused by the agglomerated sub-micron spheres could compensate for the larger surface areas provided by monodispersed nanoparticles.