Photo-induced intramolecular charge transfer from antenna to anchor groups in phenoxazine dyes

Time-resolved transient absorption spectroscopy in the visible region and density functional theory methods are used to investigate the excited-state dynamics of two metal-free organic sensitizers used in dye-sensitized solar cells (DSSCs). The triphenylamine (TPA) group in TH305 acts as an energy antenna to absorb light at approximately 381 nm. The energy absorbed by TPA can be efficiently used by DSSCs through intramolecular charge transfers from the TPA group to the cyanoacrylic acid group.