AbstractFour A‐π‐D‐π‐A type small organic molecules with 1,8‐naphthalimide motifs were successfully synthesised. The designed compounds are built of two 1,8‐naphthalimide units linked via ethynyl π‐linkages with selected functionalised donor motifs i. e. 2,2’‐bithiophene, fluorene, phenothiazine and carbazole derivative. The synthesis based on Sonogashira cross‐coupling allowed us to obtain the presented dyes with good yields. The resulting symmetrical small molecules’ optical, electrochemical and thermal properties were thoroughly investigated, and their potential applicability for the OLED devices was demonstrated. In addition, the relationship between molecular structure and properties was considered by employing experimental and theoretical studies. As a result of using various donor groups, it was possible to achieve efficient electroluminescence in the range from green (DEV4) to orange‐red light (DEV3) with a maximum luminance of 3 820 cd/m2 for DEV4. Upon the insertion of an acetylene linker to the designed molecules, the free rotation of D and A fragments, and hence the effective π‐electron communication within the entire molecule, is possible, which was confirmed by DFT studies. The obtained dyes are characterised by high thermal stability, reversible oxidation‐reduction process, satisfactory optoelectronic properties and good solubility in organic solvents, which is advisable for the application in small molecular organic light‐emitting diodes (SM‐OLEDs) technology.
摘要 成功合成了四种具有 1,8-萘二甲酰亚胺基团的 A-π-D-π-A 型有机小分子。所设计的化合物由两个 1,8-萘二甲酰亚胺单元通过乙炔基 π 链接与选定的功能化供体基团(即 2,2'-联噻吩荧光基团)连接而成。2,2'-联噻吩、芴、吩噻嗪和咔唑衍生物。基于 Sonogashira 交叉偶联的合成方法使我们能够以良好的收率获得所介绍的染料。我们对所得到的对称小分子的光学、电化学和热学特性进行了深入研究,并证明了它们在 OLED 设备中的潜在应用性。此外,还通过实验和理论研究探讨了分子结构与性能之间的关系。由于使用了不同的供体基团,因此可以实现从绿光(DEV4)到橙红光(DEV3)的高效电致发光,其中 DEV4 的最大亮度为 3 820 cd/m2。在设计的分子中加入乙炔连接物后,D 和 A 片段可以自由旋转,从而在整个分子中实现有效的 π 电子通信,这一点已通过 DFT 研究得到证实。所获得的染料具有高热稳定性、可逆的氧化还原过程、令人满意的光电特性以及在有机溶剂中的良好溶解性等特点,非常适合应用于小分子有机发光二极管(SM-OLED)技术。