Nonlinear optical response of a low symmetry phthalocyanine in the presence of gold nanoparticles when in solution or embedded in poly acrylic acid polymer thin films

•Low symmetry Zn phthalocyanine was covalently linked to Au nanoparticles.•The conjugate showed enhanced nonlinear optical behavior compared to phthalocyanine alone.•The nonlinear optical behavior further improved when embedded in poly acrylic acid.

In this article, we explored the photophysical and nonlinear optical (NLO) characterizations of low symmetry phthalocyanine (ZnPc-NH2) covalently linked to MPA-capped AuNPs (ZnPc-NH2-AuNPs) and poly acrylic acid (ZnPc-NH2-PAA). Nonlinear optical (NLO) properties of the samples were evaluated using Z-scan technique at 532 nm and 10 ns pulsed duration. We observed enhanced photophysical and nonlinear optical behaviour for the ZnPc-NH2 in presence of AuNPs. By virtue of the magnitude of absorption coefficients and other NLO optical parameters estimated in this work, ZnPc-NH2-AuNPs was found to exhibit improved nonlinear optical response compared to the ZnPc-NH2 and ZnPc-NH2-PAA. Both ZnPc-NH2-AuNPs and ZnPc-NH2 doped in PAA possess strong nonlinear absorption coefficients and very low limiting thresholds than when measured in solution.

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