Nonlinear optical properties of polyphthalocyanine porous organic frameworks

Phthalocyanines with an 18 π-electron conjugated structure have intrinsic nonlinear optical response, but their agglomeration in solution and films is a bottleneck toward their optical limiting device processing. Herein, we develop three sp3-hybridized carbon bridge polyphthalocyanine porous organic frameworks (Pc-POFs) with an enhanced nonlinear absorption effect and optical limiting properties. The strong covalent bond linked porous structures in Pc-POFs could improve their optical limiting properties by inhibiting the relaxation of the molecule and increasing their excited state absorption. Moreover, the Sn-Pc-POF which introduces a Sn metal ion in the phthalocyanine center, exhibited an optical limiting threshold of 0.37 J cm-2 at 532 nm nanosecond laser, which is highly competitive in comparison with the state-of-the-art 2D optical limiting materials such as graphene and layered transition metal dichalcogenides.