Optical limiting effects of cyano substituted distyrylbenzene derivatives

Two liquid cyano substituted distyrylbenzene derivatives (P2 and P4) have been synthesized by incorporating two tetraethylene glycol groups into the prototype scaffolds of 2,5-bis(4-(diethylamino)styryl)terephthalonitrile (P1) and 2,2'-(1,4-phenylene)bis(3-(4-(diethylamino)phenyl)acrylonitrile) (P3), respectively, for increasing their solubilities in liquid and solid substrates. The linear photophysical properties, optical/thermal stabilities and optical limiting behaviors of P1-P4 have been investigated. Results show that both P2 and P4 have significant optical limiting behaviors on 800 nm laser pulses and high thermal stabilities. However, only P4 whose cyano groups substituted on the vinylene bond exhibits good optical stability, while P2 whose cyano groups substituted on the central phenylene ring presents gradual photobleaching under illumination. Through doping P4 into a solid epoxy resin, effective optical limiting devices to 800 nm pulsed laser are fabricated.