Computational study of new pyranylidene-based D-π-A-A dyes: Effect of the change of the auxiliary acceptor

Abstract

In this study, four D-π-A-A molecules, based on pyranylidene as the donor, were developed by modification of the auxiliary acceptor. These molecules were theoretically studied using DFT and TD-DFT methods. The optoelectronic and photovoltaic properties were calculated as HOMO, LUMO, E_gap, VOC (the open-circuit photovoltage), λ_max (the maximum absorption wavelength), E_ex (the vertical excitation energies), f (the oscillator strengths) in order to study the effect of auxiliary acceptor change on the enhancement of light absorption capabilities and increase of intramolecular charge transfer ICT. The findings indicate that the D4 dye performs better than the rest of the dyes as it is characterized by a low energy gap (E_gap=1.549 eV) and a maximum wavelength (λ_max=758 nm). Therefore, the D4 dye is a good candidate for use as a DSSC sensitizer.