DFT and TD-DFT Study on Azobenzene-Based Dye Covalently Attached to Silane Coupling Agents: Toward Dye-Sensitized TiO2 Catalyst and Dye-Sensitized Solar Cell Applications

摘要

Herein, density functional theory (DFT) and time-dependent DFT (TD-DFT) studies of 4-(4-methoxyphenyl)diazenylnaphthalen-1-amine (MPDNA) covalently attached to a silane coupling agent (SCA) (namely, 4-(triethoxysilyl)butane-1,2-epoxide (OTES)) with a terminal oxirane group (MPDNA-OTES) were performed to determine the influence of SCAs on the geometry of photosensitizing dyes with multiple photoisomers or conformers. CH-O interaction between the hydroxyl group, which was formed by an epoxy ring-opening reaction between MPDNA and OTES, and the 1-naphthylamine moiety resulted in two conformers of MPDNA-OTES. The dominant trans-isomer conformation of MPDNA-OTES indicates a high driving force of electron injection (-1.61 eV) and significantly contributes to the photocurrent in dye-sensitized TiO2 catalysts and dye-sensitized solar cells. It is concluded that by combining OTES and a photosensitizing dye containing a 1-naphthylamine moiety, the CH-O interaction can be utilized to regulate the geometry of the dye to realize characteristics favorable for electron injection into the conduction band of TiO2.