1,5-萘二胺衍生物的合成及发光行为

Synthesis and Photoluminescent Properties of 1,5-Naphthalene Diamine Derivative

通过在CuI的强碱溶液中Ullmann反应合成了纯度较高的1, 5 萘二胺衍生物NPN,制备了NPN薄膜。利用紫外/可见吸收光谱和荧光发射光谱的溶剂效应对化合物NPN的发光行为进行了研究,了解了该分子在基态和激发态时的性质。差热扫描法(DSC)测定其玻璃化温度(Tg)高达129. 7℃,熔点达245. 7℃。结果表明,NPN薄膜在365nm紫外光的激发下,产生发光峰在448. 6nm附近、谱线带宽为72. 6nm的蓝光发射,发光亮度高,色纯度高。该材料具有良好的热稳定性,期望通过设计合理的器件结构实现电致蓝光发射。同时NPN保持了TPD、NPB三苯胺的基本结构特征,具有较好的给电子性,而且引入1, 5 萘二胺结构单元,使结构更紧凑,有利于空穴迁移率的提高,也可望成为优良的空穴传输材料。

In recent years aromatic diamine derivatives with good photoluminescent and hole transporting properties have been widely used in organic electroluminescence devices. However, their layer represents the weakest link in the electroluminescent structure considering the thermal stability of these materials. In this paper, 1,5-bis[N-(1-naphthyl)-N-phenyl] naphthalene diamine(NPN) with high purity was synthesized by liquid-phase Ullmann reaction and high quality film of NPN was formed on cleaned glass substrates by vacuum evaporation. NPN and its film were characterized by FTIR spectra, 1H NMR spectra, UV absorption spectra and fluorescence spectra. Differential scanning calorimeter (DSC) showed NPN has high T g (129.7 ℃) and T m (245.7 ℃). Photoluminescent properties of NPN were studied by solvent effects on UV absorption spectra and fluorescence spectra. Stokes shifts of compound NPN, solved in such solvents with different polarity as cyclohexane, chloroform and ethanol, were calculated based on Bilot-Kawski equation and they were 3 496, 5 164 and 5 402 cm -1 respectively. Distinct difference of dipole moment of NPN molecule between the ground state and excited state, which was 3.74D, showed that the charge transfer in NPN molecule occurred. In addition photoluminescent properties of NPN film were investigated by UV absorption spectra and fluorescence spectra. The results indicate that the synthetic route in NPN is efficient and safe. According to UV absorption spectra the long wave absorption peak, which has contribution to fluorescence, is attributed to charge transfer transition from nitrogen to aromatic ring. UV absorption spectra and fluorescence spectra of NPN in ethanol solvent and its film show that the absorption and emitting peak have red-shift. It is indicated the molecules of NPN in its film form “J-aggregate”. NPN film can emit intense blue fluorescence with peak wavelength at 448.6 nm and bandwidth of 72.6 nm (Chromaticity coordinates: x=0.167 7, y=0.140 0; Purity: 0.716 8) under UV excitation of 365 nm. It is demonstrated that NPN is a good hole transporting material and blue electroluminescent material with good thermal stability.