N719 Derivatives for Application in a Dye-Sensitized Solar Cell (DSSC): A Theoretical Study.

The primary goal of this investigation is to analyze the influence of the chemical modifications on the electronic structures of N719 derivatives for their use in dye-sensitized solar cells (DSSCs), by employing density functional theory. UV-vis spectra indicate that the electronic configurations are essential to study the absorption of solar irradiation and analyze the charge-transport mechanism between the electron-transport layer (ETL), the electrolyte, and the dye. Open- and closed-shell electronic configurations are related to the absorption and the excitation energies of the dye. According to the results reported here, it is possible to say that the best candidates are N719, N719-2, N719-7, and N719-8 (neutral and dianionic). They may be used as useful dye sensitizers due to their band gap and band alignment with the ETL, which contributes to having an effective charge transport during the functioning of the solar device. Another parameter that is reported in this investigation is the light-harvesting efficiency for all studied systems. This could help to improve the performance of the device, since there is an increment in the generation of charge carriers. These results could be useful as a guide for experimental investigations on chemical modifications of these sensitizers.