Optical limiting properties of 3,5-dipyrenylvinyleneBODIPY dyes at 532nm.

The optical limiting (OL) properties of 3,5-dipyrenylvinyleneBODIPY dyes that contain both electron withdrawing and donating moieties have been investigated by using the z-scan technique at 532nm in the nanosecond pulse range. The extension of the π-conjugation at the 3,5-positions with pyrenylvinylene groups results in a ca. 200nm red shift of the main BODIPY spectral band to ca. 700nm, so there is relatively weak absorbance at 532nm under ambient light conditions. Reverse saturable absorbance (RSA) profiles are observed in response to incident pulsed laser light that is consistent with a two photon absorption-assisted excited state absorption (ESA) mechanism in CHCl solution and when the dyes are embedded in poly(bisphenol carbonate A) (PBC) polymer thin films. This demonstrates that 3,5-divinyleneBODIPY dyes are potentially suitable for use in OL applications, since limiting threshold fluence (I) values of below 0.95Jcm are observed when thin films are prepared.