Containing Naphthalimide Groups Spirobifluorene Class Of Luminescent Materials Preparation And Performance

In the field of photoelectric display,the research and applications of organic optoelectronic materials and devices have made signifieant progress and development. By virtue of the following properties: direct current driving,self-luminous,small volume, fast response, wide view, simple manufacture techniques and so on, Organic Ligh-Emitting Diodes (OLED) have received more and more attention .Spirobifiuorene compounds paly an important role in the field of OLED. The existence of the orthogonal structure not only is useful for the solubility, thermal stability of materials, but also can reduce the formation of the excimer and excimer complex, so as to improve the fluorescence quantum yield. Naphthalimide derivatives with high emission efficiency are typical fluorescent reagents, but their plane rigid structure against dissolve and make for accumulation. As an electroluminescent material, the accumulation moleculars as well as the formation of the excimer and excimer complex can decrease fluorescence quantum yield, which limits the naphthalimide compounds application in the field of electroluminescence.We hope that a new kind of fluorescent material with good solubility, thermal stability and high EL efficiency can be prepared by introducing these molecules above into a new molecule, which may play a role in the field of OLED.The main achievements of this paper can be summarized as follows.Part I: the synthesis of two new Spirobifiuorene compounds SPF-NA-1 and SPF-NA-2. Using biphenyl as the starting material, left-right asymmetry compound SPF-NA-1 was prepared, through the Friedel-Crafts reaction, bromination, Grignard reaction, nitration reaction, reduction reaction and so on. Top-down asymmetry compound SPF-NA-2 was prepared also using biphenyl as raw materials, by six-step reactions such as Friedel-Crafts reaction, bromination, Gabriel synthesis, Gabriel reduction and so on. During the synthesis process, the reaction conditions of Friedel-Crafts reaction, nitration and so on were optimized. Moreover, their structures of SPF-NA-1 and SPF-NA-2 were confirmed by IR, 1H NMR, 13C NMR, LC-MS, and other testing methods.Part II: The thermal stability of SPF-NA-1 and SPF-NA-2 was characterised by TG and DTA. The results showed that their decomposition temperatures are 451℃, 448℃, separately, which indieated highly thermal stability. The optical properties of the compounds were examed by UV-vis and fluoreseence emission, both absorption and emission spectroscopy display a red shift with the increasing of solvent polarity. The onset oxidation potential of compounds were measured by CV. Onset reduction potential as well as the frontier orbital energy were evaluated by the relevant formulas.Part III: The two compounds were made into OLEDs with SPF-NA-1 and SPF-NA-2 as luminous layer. Device performances showed that the maximum emission peaks of devices SPF-NA-1 and SPF-NA-2 were at 557 nm, 551 nm respectively; the maximum external quantum efficiency 0.244%, 0.175%; the maximum brightness 387.3 cd/m2 (26.1V), 298.5 cd/m2 (27.5V). By comparison, the performences of electroluminescent device SPF-NA-1 is superior to that of the electroluminescent device SPF-NA-2.