Design And Synthesis Of Carbazole-based Second-order Nonlinear Optical Chromophore

With the rapid development of science and technology in the 21 st century,information technology has also entered a period of rapid development.Among them,information transmission,communication and other technologies attract people's attention most,but at the same time,traditional optical materials cannot meet the needs of current work,so they have a wider response band and stronger optical effects,and they also have good processing properties.And the organic second-order nonlinear optical materials with the advantages of lower material cost have attracted people's attention.At the same time,the chromophore as its basis has naturally become the target of people's attention.At present,it is still a huge challenge for scientists to obtain optical materials that can ensure practicality and excellent performance.The first is to synthesize chromophore molecules with high first-order hyperpolarizability;the second is to convert the microscopic hyperpolarizability of the chromophore molecules into the electro-optical activity of optical devices;finally,how to make organic materials with high electro-optical activity Exhibiting inherent electro-optical activity in the device is still not a small problem.In this paper,we have conducted some in-depth exploration and research on optimizing the comprehensive properties of materials.Firstly,four kinds of chromophores with different donors and acceptors,carbazole as conjugated structure and introduction of alkyl chain to enhance solubility were designed and synthesized.The structures were determined by hydrogen nuclear magnetic spectrum and carbon nuclear magnetic spectrum.And through the ultraviolet-visible light spectrum to characterize its optical absorption characteristics,using thermogravimetric analysis to characterize its thermal stability.The results show that the Td of these four chromophores are all greater than 200 °C,and they have good thermal stability.The ultraviolet absorption spectrum shows that when carbazole,a molecule with electron donating ability,is used as a conjugated structure,the matching effect of a suitable donor is better than a suitable acceptor.In addition,two second-order nonlinear photochromophore molecules containing siloxane isolating groups were designed and synthesized,and their structures were characterized by hydrogen nuclear magnetic spectroscopy and carbon nuclear magnetic spectroscopy,and their thermal stability and optical properties were characterized.The thermal stability results show that the thermal stability of G1 is weak,and decomposition occurs at 140°C,while the thermal stability of G2 is relatively high,which can reach 200°C.The chromophore and polymer polycarbonate are doped in a certain proportion to prepare the host-guest electro-optical film.It is found that the molecular packing degree of the chromophore-polymer film with the isolation group is far lower than that of the film without the isolation group.The molecule is superior to the reference chromophore of the ordinary alkyl chain.