Phthalocyanine covalent frameworks doped in PMMA matrix as high performance nonlinear optical limiter

Phthalocyanine compounds are a class of macrocyclic conjugated structures with 18 π-electrons. And have better photophysical properties. However, the π-π electron interactions lead to aggregation between phthalocyanine molecules, which affects optical limiting properties. In this work, the conjugated organic small molecule antiphenylenediamine ( PDA ) is grafted onto the phthalocyanine conjugate system through the azo condensation reaction , and the covalent organic framework polymer ( PDA-InPc ) was obtained. Then it is doped into the polymethyl methylmethacrylate ( PMMA ) matrix to produce a phthalocyanine solid device with different thickness ( PMMA-PDA-InPc ). The aggregation-free phthalocyanine covalent organic frameworks avoids intramolecular aggregation of the phthalocyanine units, and dispersing it in PMMA solid devices can also reduce intermolecular π-π stacking. As a result, the fluorescence lifetime of PMMA-PDA-InPc is τ 1  = 0.52 ns (A 1  = 95.71%) and τ 2  = 11.5 ns (A 2  = 4.29%), indicating that the phthalocyanine conjugated unit exists mainly as monomers (95.71%), while the proportion as aggregates is very small (4.29%). At the input laser energy of 9 μJ, the nonlinear absorption coefficient of PMMA-PDA-InPc device is (2.2 × 10 −9  m/W), which is significantly better than PMMA-InPc device (1.0 × 10 −9  m/W), indicating that PMMA-PDA-InPc has improved nonlinear absorption and reverse saturation absorption. This design idea of non-aggregated phthalocyanine covalent organic frameworks and its solid device expands a new idea for the development of useable phthalocyanine optical limiters .