| Recently, various novel and high performance second-order nonlinear optical (NLO) organic polymer materials, owing to their wide application in electro-optical (E-O) modulated devices and advantages superior to inorganic materials, have been prepared and investigated by numerous scientists. It is still considered to be a challenge for researchers to prepare novel polymer lattices with macroscopically non-centrosymmetric structure and in which chromophoric dipolar molecules arranged with orientation.In this dissertation, a promising methodology for fabricating high thermally stable organic second-order NLO thin films containing low molecular weight chromophoric (LMWC) molecules was sustained by the electric field-induced layer-by-layer assembly. The new LMWC molecule 3-(4-((4-((carboxymethyl)(methyl)amino)phenyl)diazenyl)phenyl)-2-cyanoacrylic acid (DRCB) was first designed and synthesized successfully, which possesses two negative groups at both ends and still retains the molecular polarity after ionized. Under the dc electric field, the density of the oriented chromophores DRCB deposited on the substrate is increased largely and upon the UV irradiation, accompanied with the transition of the ionic bonds between the layers to covalent bonds, the resulting NLO films possess excellent environmental stability and high thermal stability (the resulting films can retain 92 % of the polar order up to 200°C), which may rival the properties of the latest poled polymer films for electro-optic devices.
|
PDF Full Text Request