Donor-Modified Anthocyanin Dye-Sensitized Solar Cell with TiO2 Nanoparticles: Density Functional Theory Investigation

Nowadays, the anthocyanin natural dye has been used as a good photosensitizer for TiO2 solar cells due to its availability as well as its performance. However, the dye still has a problem regarding its narrow absorbance at 550 nm. The aim of study will extend the dye’s absorbance up to NIR spectrum, so that it will increase the TiO2 solar cell performance. The cyanidin-3-glucoside-7- diphenilamine-2'-acrylic acid (CGDA) will be introduced as the new modification of D-π-A functional material in anthocyanin dye. The investigation of the material has been carried out by the density functional theory of TD-DFT/UB3LYP/6-31+G(d,p) level. The findings show that first; the dye absorbance has broadened up to 885 nm due to the reduction of gap energy and the increase of electronic transition probabilities from 84.7% to 96.0%. Second, the molecular orbital analysis shows that both diphenylamine and acrylic acid perform as promising donor and acceptor groups for anthocyanin. Third, CGDA has the light harvesting efficiency of 46.7% surrounding NIR spectrum area. Finally, the NIR anthocyanin dye possessing HOMO of -5.536 eV and LUMO of -2.886 eV fulfills the criteria of both the effective charge transfer from LUMO dye into conduction band TiO2 and the good dye regeneration by the electrolyte redox.