Efficient electron transfer ruthenium sensitizers for dye-sensitized solar cells

Triarylamine-functionalized ruthenium dyes J13 and J16 were synthesized as novel efficient dye-sensitized solar cells (DSSCs). Under standard global AM 1.5 solar conditions, the J13- and J16-sensitized solar cells demonstrate short circuit photocurrent densities of 15.65 and 15.71 mA cm^-2, open circuit voltages of 703 and 702 mV, fill factors of 0.712 and 0.701, and overall conversion efficiencies of 7.83% and 7.73%, respectively. The N719 dye under identical measurement conditions gives 7.91%. DFT/TDDFT calculations were performed on the two sensitizers to gain insights into their structural, electronic, and optical properties. These results indicate that the triarylamine ligand acts as an electron donor in a manner similar to thiocyanato ligands and Ru metal, and the TDDFT calculations predict that the absorption in the visible region originates from electron transfer from the electron donor groups to the anchoring ligand dcbpy, through which excited electrons are directly transferred to TiO₂. It is suggested that the triarylamine-functionalized ruthenium dyes are highly promising for DSSCs.