Study On The Effect Of Isolating Groups On The Properties Of Organic Nonlinear Optical Chromophores

Since the 21st century,with the rapid development of the Internet,people's demand for high speed communication is increasing.The traditional electronic information transmission was unable to meet people's demands.The optical information communication technology with faster transmission speed and larger bandwidth is bound to receive great attention.Organic electro-optical?OEO?materials attracted great attention owing to their potential applications in the field of electro-optic modulator and high-speed information transmission.Nonlinear optical?NLO?chromophore is the core components of organic electro-optical materials.The introduction of isolation group is one of the important strategies to improve the performance of organic non-linear optical chromophore such as improving the electro-optical coefficient and stability of electro-optical materials.In this paper,the organic electro-optic materials with high electro-optic coefficient and good stability were obtained by reasonable design of non-linear optical chromophores and introduction of appropriate isolation groups.And the influence of isolation groups on the performance of organic non-linear optical chromophores is explored.1.Two chromophores A-B were designed and synthesized with diethylamine benzene-based donor,isophorone derivatived bridge and TCF or CF₃-Ph-TCF acceptor.The donor and conjugated bridge of chromophore was modified with a rigid steric pentafluorobenzene group.Chromophore A-B possess all trans configuration and large first-order hyperpolarizability.The rigid steric groups on the donor and conjugated bridge can effectively weaken the electrostatic interaction between chromophores and reduce the compact packing of molecules,thus converting the microscopic first-order hyperpolarizability???of chromophores into the macroscopic electro-optical coefficient(r₃₃)more effectively.The thermal decomposition temperature?T_d?of chromophore A-B is higher than 220?,showing excellent thermal stability.After poling,the polymer films doped with 30 wt%chromophore A-B have large electro-optic coefficients(r₃₃)of 115 pm/V and 213 pm/V,respectively,which are higher than that of analogue chromophores without modified isolation group.2.Four nonlinear optical chromophores A-D functionalized with pentafluorobenzene?FD?or benzene rings?HD?on both the dialkyl aniline donor and isophorone-derived bridge have been designed and synthesized.The supramolecular self-assembly of chromophores B and D by?-?stacking of HD/FD groups can effectively improve the polarization efficiency and orientation stability of the materials.Different from the traditional host-guest electro-optic polymers which containing Chromophore A or Chromophore B individually,the chromophore number density of the neat binary self-assembly electro-optic thin film B/D is more than 6.0×10²⁰ molecular/cm³,and the r₃₃ value is as high as 275 pm/V.After annealing at room temperature for 1000 h,the r₃₃ value can still keep 91%of the original value,while the neat chromophore B film can only maintain 53%of the original value.