Computational Study of Cresyl Violet Covalently Attached to the Silane Coupling Agents: Application to TiO-Based Photocatalysts and Dye-Sensitized Solar Cells.

The covalent attachment of photosensitizing dyes to TiO using silane coupling agents (SCAs) is a promising strategy for enhancing the photocatalytic activity of TiO-based photocatalysts and the photovoltaic conversion of dye-sensitized solar cells (DSSCs). This approach can control the geometry and orientation of the photosensitizing dye on the TiO surface. In this study, a density functional theory (DFT) and time-dependent DFT (TD-DFT) investigation was carried out on cresyl violet (CV) covalently attached to SCAs with a terminal oxirane group (OTES-Cn) to reveal the influence of OTES-Cn on the geometry of the photosensitizing dyes. The potential of CV covalently attached to OTES-Cn (CV-OTES-Cn) to act as a photosensitizing dye was also analyzed. The hydroxyl group formed by the epoxy-opening reaction between CV and OTES-Cn strongly influenced the geometry of CV-OTES-Cn, which was attributed to a CH-O interaction. Additionally, TD-DFT, frontier molecular orbital and molecular electrostatic potential calculations revealed that CV-OTES-Cn has excellent optical properties and electron injection ability. In particular, the characteristics of the unbent conformation of CV-OTES-Cn are expected to contribute significantly to the photocurrent in TiO-based photocatalysts and DSSCs. These findings enhance the understanding of the covalent attachment strategy using SCAs and contribute to improving TiO-based photocatalysts and DSSCs.