Influence of para-orientating Methoxyl Units on the Electronic Structures and Light Absorption Properties of the Triphenylamine-based dyes by DFT Study

Abstract

The geometries, electronic structures and absorption spectra of the two organic triphenylamine-based dyes TASt-CA and TA-DM-CA, containing identical electron donors and acceptors but the different conjugated bridges, were studied by density functional theory (DFT) at the B3LYP and PBE1PBE levels, respectively. The influence of para-orientating methoxyl units on the electronic structures and light absorption properties of the dyes and the consequent photovoltaic performance of the dye-sensitized solar cells (DSSCs) were investigated in detail. The results indicate that the introduction of the para-orientating methoxyl units into the conjugated bridge induces the increased absorption wavelength as well as the more negative E HOMO corresponding to the bigger driving force ( − E HOMO ) for dye reduction, which together improve the photovoltaic performance of TA-DM-CA, although there is a decline of the open circuit voltage caused by the more negative E LUMO .