Enhancement of two photon absorption properties by charge transfer in newly synthesized aza-boron-dipyrromethene compounds containing triphenylamine, 4-ethynyl-N,N-dimethylaniline and methoxy moieties

The effects of substitution and charge transfer on linear and nonlinear optical absorption (especially two photon absorption) properties of aza-BODIPY containing triphenylamine, 4-ethynyl-N,N-dimethylaniline and methoxy moieties were investigated by ultrafast pump probe spectroscopy technique. Fluorescence and ultrafast pump probe spectroscopy experiments revealed that aza-BODIPY compounds with good electron donating moieties (triphenylamine and 4-ethynyl-N,N-dimethylaniline moieties) have charge transfer from electron donating parts of the molecules to aza-BODIPY core. The two photon absorption cross sections increase with the electron donating strength. Maximum two photon absorption cross section is obtained as 126 GM at telecommunication wavelength (1310 nm) for aza-BODIPY compound containing triphenylamine, 4-ethynyl-N,N-dimethylaniline. Our results indicate that charge transfer enhances two photon absorption properties.