Impact of substitution and self-aggregation on photoelectric and charge transfer characteristics in JD21 analogues.

In addition to π-linkages and acceptors, the nature of donor moiety plays a vital role in tuning organic dye performance. Here, to assess the substitution effect of peripheral groups in donor moiety, two electron-donating and two electron-withdrawing groups are, respectively, introduced in the ullazine ring of JD21. It is shown that the introduction of trifluoromethyl group in JD-dye (JD21-CF) keeps the system to be of both the comparable light-harvesting and anti-aggregation ability to the original JD21 dye. It is regarded as a potentially efficient strategy to prepare JD-dyes or even other organic dyes. Additionally, the investigation on adsorbed dimeric dyes reveals that the electronic distribution with the highest occupied molecular orbital localizing on one dye molecule and the lowest unoccupied molecular orbital localizing on the TiO nanoparticle in the H-2-slip@TiO or F-2-slip@TiO configuration suggesting a weaker electronic coupling between two dyes. This type of adsorbed configuration with both dye dissociation is thus proposed to be dominant in an optimal solar cell based on the corresponding photoelectric characteristics. Our results clearly show a dependency of the dye performance on substituent groups. [ABSTRACT FROM AUTHOR]