Facet selective engineered TiO2 as photoanode for dye sensitized solar cells

Dye-sensitized solar cells (DSSCs) often suffer from inefficient charge transport and recombination losses, limiting their power conversion efficiency. Advancing beyond conventional TiO 2 photoanodes requires deliberate control of charge dynamics at the crystallographic level. In this study, anatase TiO 2 nanocrystals with well-defined characteristic facets were used as photoanodes in DSSCs. A hydrothermally modified sol-gel method was used to synthesize these nanocrystals, utilizing cetyltrimethylammonium bromide (CTAB) as a morphology-controlling agent and titanium tetra isopropoxide (TTIP) as a precursor. Under an acidic pH of 3, the process facilitated the effective adherence of CTAB molecules to the high-energy facets of TiO 2 , resulting in crystal growth elongation along specific directions and facet exposures. The photovoltaic conversion efficiency of DSSCs based on nanocrystalline TiO 2 was compared with that of DSSCs utilizing commercial-grade P25 TiO 2 . The remarkable enhancement in photovoltaic activity of nanocrystalline TiO 2 -based DSSCs was attributed to the increased number of active sites for dye adsorption, leading to enhanced light absorption. Furthermore, high-energy facets significantly improved electron mobility and facilitated spatial separation of photogenerated charge carriers. The photoanodes incorporating the as-synthesized TiO 2 nanocrystals as the active layer exhibited an impressive photoconversion efficiency of 6.6%, markedly surpassing the reference photoanode's efficiency. This study underscores that rational crystallographic design of single-component TiO 2 provides a material-intrinsic and potent pathway to optimize the charge transport dynamics to a greater extend in DSSCs.