Quantum chemical designing of efficient TC4-based sensitizers by modification of auxiliary donor and π-spacer

In the present study, ten metal-free dyes for dye-sensitized solar cells (DSSCs) have been designed. These dyes have designed by structural modification of TC4. Density functional theory was used for structure optimization and determination of photophysical properties. These dyes contain triphenylamine as electron donor and cyanoacrylic acid as electron acceptor. Five π-spacers are used to connect the donor and acceptor. Two auxiliary donors are also used to assist the donor. Results of this study indicate that stronger electron-donating auxiliary groups and longer π-conjugation enhance, while electron-withdrawing fluorine at a π-spacer decreases the performance of dyes in DSSC. As compared to auxiliary electron donors, π-spacers have a strong impact on the performance of the dyes in the DSSCs. Major absorption peaks of all dyes were in the visible region. These absorption peaks are associated with the π-π* transitions of the entire molecule. From calculations it is clear that all dyes will be good photosensitizers in DSSC. The present calculations will provide new ways for experimentalists to synthesize high-performance dyes.