Effect of intramolecular charge transfer on the two-photon absorption behavior of multibranched triphenylamine derivations

Solvent polarity effect on the absorption spectra and fluorescence spectra of a series of multibranched structure triphenylamine derivations (Ph-G0, Ph-G1, and Ph-G2) were analyzed to reveal the factors that determine the two-photon absorption (TPA) ability in these molecules. It was found that the dominate factor is the extent of intramolecular charge transfer upon photoexcitation, rather than coherent coupling between branches. This result suggests that it is more effective to change the electron withdrawing ability or electron giving ability of branches and core than simply increase the number of branches for enhancing the TPA ability in multibranched structure molecules. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3692076]