Study On The Nonlinear Optical Mechanism Of The Phthalocyanine Complexes Of The Fourth Main Group Element

The third-order nonlinear optical(NLO)materials show potential application prospect in optical communications,optical switching and optical limiting fields.So,there is currently intense research interest in developing new third-order NLO materials.Phthalocyanines are a class of good promising organic compounds with 18π-electrons conjugated system and easily modified structure,which easily hybrid with other functional materials,and have highly stability against heating,optics and chemical stability.In order to research the correlation between molecular structure and the third order NLO properties systematically,and obtain the material with large nonlinear susceptibilities,phthalocyanines containing group IVA central elements with two kinds of substituents were synthesized.Graphene oxide is one kind of carbon based materials with 2Dπ-electrons conjugation system.It has excellent third-order NLO properties which can be tuned by altering the proportion of sp~2 hybrid carbon to sp~3 hybrid carbon.For the sake of obtaining materials with excellent NLO effects,phthalocyanines has been hybrided with graphene oxides to investigate the NLO effects of composites.Tetra-β-(3-pyridyloxy)phthalocyaninatotin(IV)hydroxide,Tetra-β-(3-pyridyloxy)phthalocyaninatolead(II),Tetra-α-(4-pyridyloxy)phthalocyaninatolead(II)and Tetra-α-(4-tert-butylphenoxy)phthalocyaninatolead(II)were synthesized.The phthalocyanine samples were characterized by UV-Vis spectrum,FT-IR spectrum and MALDI-TOF mass spectrum.We use the Z-scan technique with laser flash photolysis technique to investigate the NLO properties of phthalocyanine complexes and elucidate the related mechanism.The result shows that the NLO absorption effect of phthalocyanine complexes primarily originated from the reverse saturable absorption of the first triplet excited state.The correlation between the molecular structure of phthalocyanine complexes and NLO properties were investigated,and the effect of the central metal in the same group with identical substituents,the central metal in the different groups with identical substituents,different kinds of substituents with identical substitution positions and identical kinds of substituents with different substitution positions on the third-order NLO properties were discussed.In order to further enhance the NLO properties of materials,the phthalocyanines with the better nonlinear absorption effect was mixed with graphene oxide.The third order NLO properties of the hybrid materials were investigated using the Z-scan technique and laser flash photolysis technique,and the NLO mechanism was studied.The Z-scan curves display a conversion of nonlinear absorption effect between saturable absorption and reverse saturable absorption.This is mainly ascribed to exist sp~2 and sp~3hybrid carbon structures in graphene oxide simultaneously,which two hybrid structure require different laser energy.The result also shows that there is an electron transfer process between phthalocyanines and graphene oxides in composites.The NLO properties of composite system were significantly enhanced compared to the corresponding phthalocyanines and graphene oxides,respectively.