Key Laboratory of Organofluorine Chemistry and Laboratory for Polymer Materials, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road, Shanghai 200032, PR China.
J Phys Chem B. 2010 Aug 19;114(32):10374-83. doi: 10.1021/jp104710y.
Monodispersed oligomers have been widely developed and used in different optoelectronic areas due to their well-defined molecular structures, high purity, and solution processability. Star-shaped oligomers are especially interesting for OLED application because of their antiaggregation abilities and stable electroluminescence. In addition, star-shaped donor-pi-acceptor conjugated molecules are known to afford good nonlinear optical and two-photon absorption properties due to the intramolecular charge transfer and cooperative enhancement effects. In this context, three generations of highly soluble 1,3,5-triazine based donor-pi-acceptor compounds, TFT1, TFT2, and TFT3, were prepared through a convergent synthetic strategy and their optoelectronic properties were fully studied, which showed distinct correlations with the structures. Closed-aperture and open-aperture Z-scan methods were employed to measure the nonlinear refractive index and two-photon absorption properties of the oligomers, respectively. TFT1 showed a high nonlinear refractive index of 4.14 x 10(-12) esu in THF solution with an excitation wavelength of 800 nm. Also, TFT1 exhibited a large two-photon absorption cross section of 234 GM and a frequency up-converted two-photon excited fluorescence with a lambda(TPEF)(max) value of 527 nm under 800 nm laser irradiation with a pulse duration of 140 fs. OLED devices using the spin-coated films of these oligomers as an active layer showed intensive blue electroluminescence with a maximum luminance of 3093 cd/m(2) at a current efficiency of 1.47 cd/A from TFT1.
由于具有明确的分子结构、高纯度和溶液加工性能，单分散低聚物在不同的光电领域得到了广泛的发展和应用。由于具有抗聚集能力和稳定的电致发光性能，星形低聚物特别适用于 OLED 应用。此外，由于分子内电荷转移和协同增强效应，星形给体-π-受体共轭分子通常具有良好的非线性光学和双光子吸收性能。在这种情况下，通过收敛合成策略制备了三代高度可溶的基于 1,3,5-三嗪的给体-π-受体化合物 TFT1、TFT2 和 TFT3，并对其光电性能进行了充分研究，结果表明其与结构之间存在明显的相关性。采用闭路和开路 Z 扫描方法分别测量了低聚物的非线性折射率和双光子吸收性能。TFT1 在 THF 溶液中在 800nm 的激发波长下表现出 4.14 x 10(-12) esu 的高非线性折射率。此外，在 800nm 激光辐照下，TFT1 表现出大的双光子吸收截面 234 GM 和频率上转换双光子激发荧光，其 lambda(TPEF)(max)值为 527nm，脉冲持续时间为 140fs。使用这些低聚物的旋涂薄膜作为有源层的 OLED 器件显示出强烈的蓝色电致发光，在电流效率为 1.47cd/A 时，TFT1 的最大亮度为 3093cd/m(2)。
