Molecular engineering of organic materials for nonlinear absorption in the visible range:: the excited states of tetraphenyl-diamine derivatives

We report on nonlinear absorption measurements of tetraphenyl-diamine dyes developed for use as transparent materials for optical limiting applications in the visible range. All the excited state properties which are relevant to the process are investigated experimentally using three different and complementary nonlinear spectroscopy tools. Through a modification of the substitution of the peripheral benzene rings of the original dye, we could significantly improve its optical limiting activity, especially in the red region where it had a rather poor efficiency.