| With the development of optical communication and optoelectronic technology,molecular materials with nonlinear functions have received extensive attention.Among them,third-order nonlinear optical(NLO)materials have received increasing attention due to their potential applications in many fields,such as optical communication,optical switching,optical data storage,and optical limiting.Among these materials,metal complexes are considered to be good third-order nonlinear optical materials.Although the synthesis conditions of some complexes are harsh,they usually exhibit diverse spatial structures and rich electronic properties due to the presence of metal ions.This greatly improves their nonlinear performance.However,there are few examples of improving the third-order nonlinear properties of metal complexes by combining them with other materials.Therefore,it is of great significance to combine complexes with other organic/inorganic materials with nonlinear properties to improve the nonlinear properties of materials.In this paper,two azobenzene complexes with good third-order nonlinear optical properties were selected first.The complexes have a large π-electron conjugated system,and the existence of N=N double bond also provides a good channel for electron flow in the molecule.Subsequently,we composited the azobenzene complex with PANI to achieve efficient electron transfer between the azobenzene complex and PANI,and prepared composites with good third-order nonlinear properties.Finally,we made composite films by inter-doping azobenzene complexes and their composites with high-molecular polymers to study the third-order nonlinearity of the composite films.This paper mainly includes the following three parts:(1)First,we synthesized two complexes 1 and 2 with the azobenzene derivative H2L as the ligand,and composited the two azobenzene complexes with nano-PANI respectively to obtain the composites PNAI@1 and PNAI@2.The structure and purity of the compounds were tested by X-ray powder diffraction,thermogravimetric analysis and infrared spectroscopy.On this basis,the morphology,size and element distribution of the compounds were characterized by SEM and EDS Mapping.Finally,we used electrochemical analysis and EPR experiments to understand the improvement of the photoelectric properties of the composites by PANI.The experimental results show that 1 and 2 are successfully composited with PANI and have good optoelectronic properties.(2)We obtained the composite films by doping 1,2 and their composites with high molecular polymers PVA and PMMA.The composite films were characterized by Xray powder diffraction,thermogravimetric analysis,UV-Vis diffuse reflectance and infrared spectroscopy.In addition,the morphology and element distribution of the composite films were characterized by SEM and EDS Mapping.The experimental results show that the microcrystalline 1 and 2 and their composites with PANI have been successfully doped into the PVA and PMMA matrices and maintain their original structures.(3)Finally,the nonlinear optical responses of these composite films were analyzed by picosecond Z-scan technique.The results show that 1 and 2 in the solution state are consistent with the nonlinear signal of the composite film,and both have reverse saturable absorption and self-defocusing refractive properties.But it is worth mentioning that the third-order nonlinear coefficient of the composite films is improved by nearly two orders of magnitude compared with 1 and 2 in the solution state.PNAI@1 and PNAI@2 composite films also has reverse saturable absorption behavior,and the addition of PANI also improves the nonlinear absorption performance of the material.Miraculously,the addition of PANI changes the arrangement of electron clouds inside the material,which leads to the conversion of 1 and 2 from defocusing refraction to self-focusing refraction.At the same time,the two high molecular polymer substrates,PVA and PMMA,also have different effects on the nonlinear properties of the compounds. |
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