Improved optical limiting of triazine-linked mono-, bis- and tris-phthalocyanines

We studied the photophysical dynamics and optical limiting properties of a series of triazine-linked mono-, bis-, and tris-phthalocyanines with central metal In for 532nm-7ns laser pulses. We used Crank-Nicholson numerical method to solve two-dimensional paraxial field equation and rate equations. Phthalocyanines are simplified to a five-level model to simulate the optical dynamical processes. We found the sequential (singlet–singlet) × (triplet–triplet) two-photon absorption is the prominent optical limiting mechanism for long pulses. Our work indicates that triazine-linked mono-, bis-, and tris-phthalocyanines exhibit excellent optical limiting behaviors, and tris-phthalocyanine shows the best properties. Graphical abstract