Kang Hu, Evmenenko Guennadi, Dutta Pulak, Clays Koen, Song Kai, Marks Tobin J
Department of Chemistry and the Materials Research Center, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
J Am Chem Soc. 2006 May 10;128(18):6194-205. doi: 10.1021/ja060185v.
A novel type of "X-shaped" two-dimensional electro-optic (EO) chromophore with extended conjugation has been synthesized and characterized. This chromophore is found to exhibit a remarkably blue-shifted optical maximum (357 nm in CH(2)Cl(2)) while maintaining a very large first hyperpolarizability (beta). Hyper-Rayleigh Scattering (HRS) measurements at 800 nm provide a beta(zzz) value of 1840 x 10(-30) esu. Self-assembled thin films of this chromophore were fabricated via a layer-by-layer chemisorptive siloxane-based approach. The chromophoric multilayers have been characterized by transmission optical spectroscopy, advancing contact angle measurements, synchrotron X-ray reflectivity, atomic force microscopy, and angle-dependent polarized second harmonic generation spectroscopy. The self-assembled chromophoric films exhibit a dramatically blue-shifted optical maximum (325 nm) while maintaining a large EO response (chi(2)(333) approximately 232 pm/V at 1064 nm; r(33) approximately 45 pm/V at 1310 nm). This work demonstrates an attractive approach to developing EO materials offering improved nonlinearity-transparency trade-offs.
一种具有扩展共轭的新型“X 形”二维电光（EO）发色团已被合成并表征。发现该发色团在保持非常大的第一超极化率（β）的同时，呈现出显著蓝移的光学最大值（在 CH₂Cl₂ 中为 357 nm）。在 800 nm 处的超瑞利散射（HRS）测量给出了 1840×10⁻³⁰ esu 的 β(zzz) 值。通过基于层间化学吸附硅氧烷的方法制备了该发色团的自组装薄膜。通过透射光谱、前进接触角测量、同步加速器 X 射线反射率、原子力显微镜和角度相关的偏振二次谐波产生光谱对发色团多层膜进行了表征。自组装发色团薄膜呈现出显著蓝移的光学最大值（325 nm），同时保持较大的电光响应（在 1064 nm 处 χ(2)(333) 约为 232 pm/V；在 1310 nm 处 r(33) 约为 45 pm/V）。这项工作展示了一种开发电光材料的有吸引力的方法，该方法能提供改进的非线性 - 透明度权衡。
