Design,Synthesis And Characterization Of Second-order Nonlinear Optical Materials Based On Ftc Chromophore

The rapid development of information technology is inseparable from the storage,processing and transmission of various informations.Second-order nonlinear optical materials have attracted researchers for decades of research and exploration due to their outstanding performance in high-speed optical communication,fast photoelectric modulators,optical switches,and high-density optical memories.Compared with inorganic second-order nonlinear optical materials,organic second-order nonlinear optical materials have outstanding advantages.They have larger second-order nonlinear optical effects,higher optical damage threshold,excellent processing performance and ultra-fast response.For organic second-order nonlinear optical materials,how to convert the microscopic hyperpolarizability ? value of the chromophore into macroscopic electro-optic effect and maintain stability for a long time is the biggest problem in this field,and in addition to the device processing of optical materials.Good thermal stability and optical transparency are also basic requirements.In the development of organic second-order nonlinear optical materials,researchers have designed and synthesized many organic second-order nonlinear optical chromophores with high photoelectric properties.Based on these chromophores,numerous organic second-order nonlinear optical macromolecular materials with different topologies have been developed,some of which have high optoelectronic properties and good thermal stability.Based on the FTC chromophore with high photoelectric properties,a series of organic second-order nonlinear optical macromolecular materials with different topologies were designed,synthesized and characterized,and their second-order nonlinear optical coefficient values(d₃₃)were tested.According to the progress of the experiment,this paper can be roughly divided into the following four chapters.Chapter one:The main content is a brief introduction to the research background of organic second-order nonlinear optical materials,the basic structure of chromophores and the influence of different structures on the photoelectric properties of chromophores,macromolecules with different topologies based on chromophore and its photoelectric properties and thermal stability,and then based on the previous research,put forward the design ideas of this paper.Chapter two:The author designed and synthesized of a side-by-side molecule connecting three TTC chromophore donors through an alkyl chain.Compared with a single FTC chromophore,the second-order nonlinear optical effect test results show that it has better macroscopic NLO activities,the NLO coefficient d₃₃ value was as high as 255 pm/V and can retain its initial second-order nonlinear optical coefficient of 80%at a temperature of 149?.Chapter three:The authors used the azo chromophore as the nucleus of the dendrimer,and connected the FTC chromophore through a mild"click reaction"to synthesize two dendrimers,named D1 and D2,respectively.D1 molecule contains three azo chromophores and two FTC chromophores,the D2 molecule consists of one azo chromophore and four FTC chromophores.The test results show that the dendrimer D2 with more FTC chromophore fragments has better overall performance,it has good film formation,high second-order nonlinear performance with the d₃₃value of 270 pm/V,and can retain its initial second-order nonlinear optical coefficient of 80%at a temperature of 155?.Chapter four:Considering that it is difficult to synthesize high generation dendrimers,the author bonded low generation dendrimers to the carbazole polymer backbone through post-functionalization methods,and synthesized two kinds of dendronized polymers PG1 and PG2 which contain two and three FTC chromophores,respectively.A linear polymer PG0 was also synthesized as a control.The experimental results show that the dendronized polymers have higher photoelectric properties and higher thermal stability.Especially for PG2,the NLO coefficient d₃₃value was as high as 282 pm/V.Besides,it had good temporal stability in which 80%of its maximum value retained at the high temperature of 129?.