Optical Nonlinearity Study Of Sulfonic Phthalocyanine/graphene Electrostatic Self-assembled Film

The researching on the application of optical devices based on the preparation of the nonlinear optical materials.Composite thin films with ordered structure are an active part in the field of the nonlinear optieal(NLO)materials research on aceount of their excellent nonlinear optical properties.Therefore,the preparation of the materials for compound films is imperative.In order to obtain solid composite films with larger optical nonlinearity,electrostatic self-assembled film containing α-SLPcCo,α-PhSPcNi,β-PhSPcH2,CoPc(COOH)8 and GO,poly diallyl dimethyl diallyl ammonium chloride chloride(PDDA)were fabricated by electrostatic self-assembled technique.The microstructures of these films were characterized using atomic force microscopy,UV-Vis absorbance spectrum,Raman spectrum and Scanning electron microscope.Homogeneous nanoparticles were formed in the films as a result of overlapping of phthalocyanine macrocyles and graphene moleculars.The third-order nonlinear optical properties ofα-SLPcCo/PDDA/GO,α-PhSPcNi/PDDA/GO,β-PhSPcH2/PDDA/GO and CoPc(COO-Na)8/PDDA/GO thin films were investigated using Z-scan technique with laser pulses of 4 nanosecond at the wavelength of 532 nm.Four kinds of film exhibited reverse saturable absorption.The third-order nonlinear optical properties of phthalocyanine/graphene composite films were stronger than that of phthalocyanine films,especially much stronger than that of the corresponding phthalocyanine solution and grapheme solution.α-tetra-[2-(2-hydroxy)ethyloxy]ethyloxyphthalocyanine[MPc(3DG)4,M=Co、Ni、Cu、Zn、Pb],α-tetra-(5-hydroxypentyloxy)phthalocyanine[MPc(3TD)4,M=Cu、Zn、Pb],and metal-free phthalocyanine were synthesized.The phthalocyanine samples were characterized by UV-Vis spectral,FT-IR and MOLDI-TOF mass spectra.The third-order nonlinear optical properties of phthalocyanine samples were investigated using Z-scan technique,by which the nonlinear absorption coefficient,third-order nonlinear optical susceptibility and second-order nonlinear superpolarizability were obtained.Fluorescence lifetime,fluorescence quantum yield and triplet lifetime were acquired by fluorescenee spectra and transient absorption spectra in order to study the properties of excited state and the nonlinear optical mechanism.The nonlinear optical properties were attributed to reverse saturable absorption effect arised from the triplet excited state.The relationship between the molecular structures and the nonlinear optical properties of the complexes were investigated,and the affect of the peripheral substituents on the third-order nonlinear optical properties was discussed.