Quantum chemical and photovoltaic modeling of D-π-A organic dyes based on substituted arylamine electron donors in dye sensitized solar cells

In the present research, we designed four tunable triphenylamine (TPA) based organic dyes by applying various aminated electron donor groups and screened their electron donating effects on the electronic, optical and photovoltaic properties of the dyes for application in dye sensitized solar cells (DSSCs). In this respect, density functional theory (DFT) and time-dependent density functional theory (TD-DFT) approaches were applied to investigate the enhanced electron donating effect of substituted TPA dyes on the strength of conjugation with thiophene and a C-C triple bond in the pi-spacer fragment that led to a considerable effect on absorption properties, light harvesting efficiency and panchromatic sensitization of the designed dyes in DSSCs. In fact, since the most significant impediment of TPA-based organic dyes for high photovoltaic performance in DSSCs is their low absorption in the near-infrared spectrum, we aimed our modeling to introduce molecular dyes with reduced frontier molecular orbital energy gaps and hence, the favoured red-shift absorption spectra. Moreover, we have computationally concentrated on the photovoltaic performance of our novel dyes in DSSCs and demonstrated that employing aminated electron donating groups in TPA based organic dyes notably tunes the electron injection and regeneration driving forces and hence leads to higher power conversion efficiencies.