The effect of aggregation on the nonlinear optical absorption performance of indium and gallium phthalocyanines in a solution and co-polymer host

The nonlinear optical properties (NLO) of Pcs can be modified by substituting different metal atoms into the ring or altering peripheral and axial functionalities. In this study, nonlinear optical absorption properties of tetra-substituted gallium and indium phthalocyanine complexes both in solution and polymeric film have been investigated by open aperture Z-scan measurements with nanosecond pulses at 532 nm. All investigated compounds exhibited reverse saturable absorption for both solution and film experiments. The investigated compounds in the solution showed better nonlinear optical absorption properties than polymeric films. The observed nonlinear optical absorption differences depending on the aggregation are discussed using the ultrafast dynamics and decay processes of excited states found from femtosecond pump-probe spectroscopy with white light continuum experiments. Highlights: ► The effect of aggregation on the nonlinear absorption and the excited state lifetimes were studied. ► UV–Vis absorption spectra revealed that organization of investigated molecules in PMMA films show H-aggregation. ► Fast transitions (intermolecular energy transfers) in PMMA films were observed. ► Intermolecular energy transfer due to aggregation reduces transition to triplet levels. ► Aggregation reduces RSA signal observed in OA Z-scan experiments for the samples in a host PMMA polymer matrix