An Iron-Based Photosensitizer with Extended Excited-State Lifetime: Photophysical and Photovoltaic Properties

Herein, we report a homoleptic iron complex bearing tridentate bis-carbene (CNC) ligands designed for sensitization of TiO2 photoanodes. Its excited state has been characterized by ultra-fast transient spectroscopy and time-dependent density functional theory (TD-DFT) computations, which reveal a record triplet metal-to-ligand charge-transfer ((MLCT)-M-3) excited-state lifetime (16 ps). The new dye was efficiently chemisorbed on TiO2 and promoted electron injection and photocurrent generation in a dye-sensitized solar cell upon solar irradiation.