New class of two-photon-absorbing chromophores based on dithienothiophene

Novel two-photon absorption (TPA) chromophores are synthesized; they have dithienothiophene (DTT) as a pi-center which is attached by electron donor (D) or electron acceptor (A) at each end through a pi-conjugation. Their TPA cross section, measured using nanosecond- as well as femtosecond-pulsed laser, exhibits one of the largest values known so far. This is attributable mainly to the unique electronic properties of DTT.