Enhanced efficiency of DSSCs by co-sensitizing dyes with complementary absorption spectra

Abstract

In order to understand the mechanism of molecular improvement by dye co-sensitization at the microscale, a co-sensitized molecular system is simulated using density functional theory and time-dependent density functional theory. The single molecules AJ502 and TZ101 are first evaluated globally, with AJ502 having better spectral response performance and higher light absorption efficiency. The AJ502 molecule has a strong electron accept ability and intramolecular charge transfer phenomenon. These factors make the short circuit current density and photoelectric conversion efficiency of AJ502 have a very prominent performance. At the same time, the co-sensitization properties of AJ502 and TZ101 are investigated, finding that the overall molar extinction coefficient and charge transfer phenomenon of the co-sensitized system are enhanced. Most importantly, a detailed comparison of the effects of the two co-sensitized conformations on dye-sensitized solar cell devices shows that the H-H conformation is the most advantageous due to its more robust structure, pronounced red shift in the absorption spectrum and larger amount of intermolecular charge transfer.