极化
热稳定性
材料科学
发色团
折射率
功勋
聚合物
光电子学
光学
分析化学(期刊)
复合材料
化学
光化学
有机化学
物理
电介质
铁电性
作者
Huajun Xu,Fenggang Liu,Delwin L. Elder,Lewis E. Johnson,Yovan de Coene,Koen Clays,Bruce H. Robinson,Larry R. Dalton
标识
DOI:10.1021/acs.chemmater.9b03725
摘要
The development of organic electro-optic (EO) materials that concurrently possess a high electro-optic coefficient (r33), high index of refraction, and long-term or high-temperature stability of chromophore alignment has been a crucial goal. To address this challenge, we developed a crosslinkable EO system consisting of two chromophores, HLD1 and HLD2, which can be electric field poled and then thermally crosslinked in situ to form a stable EO material. This approach avoids the necessity for nonlinear optically inactive materials such as polymers or small molecule cross-linkers, thus resulting in high chromophore density (>5 × 1020 molecules/cm3) and high index of refraction (n = 1.89 at 1310 nm) for HLD1/HLD2. Different ratios of HLD1 and HLD2 were evaluated to optimize poling efficiency and thermal stability of the poling-induced order. With 2:1 HLD1/HLD2 (wt/wt), a maximum r33 of 290 ± 30 pm/V was achieved in a cross-linked film. Thermal stability tests showed that after heating to 85 °C for 500 h, greater than 99% of the initial r33 value was maintained. This combination of large EO activity, high index of refraction, and long-term alignment stability is an important breakthrough in EO materials. HLD1/HLD2 can also be poled without the subsequent cross-linking step, and even larger maximum r33 (460 ± 30 pm/V) and n3r33 figure of merit (3100 ± 200 pm/V) were achieved. Hyperpolarizabilities of HLD and control molecules were analyzed by hyper-Rayleigh scattering and computational modeling with good agreement, and they help explain the high acentric order achieved during poling.
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