Study On Oxidative-coupling Copolymerization Of Some Aromatic Molecules And The Light Emitting Properties Of The Products

As a new kind of organic semiconductor, conjugated polymers have very extensively applications in scientific frontier and high-technology. One of the most important application of conjugated polymers is used as active emitting layers in the farbrication of polymer light emitting diodes (PLED). Since Burroughes et al. reported the first PLED used PPV as the emitting material in 1990 in NATURE, large numbers of researches were devoted to this subject by the scientists and industries. The performance of PLED acquire great achievement during the last decade, those efficiency, brightness and device lifetime of PLED have been improved significantly, approaching the practiced application and commerzialization. The blue, green and red light emitting materials all have good improved performance. The polymeric light emitting materials offer advantages in comparison to their inorganic counterparts, such as easy processibility, low price, emissive color tunability and so on.The oxidative-coupling polymerization is the most simple and convenient synthesize method to prepare the conjugated polymers, which can connects the two aromatic ring directly. The convenient conductive polymers, such as poly(p-phenylene), polythiophene and polypyrrole can be prepared by oxidative-coupling polymerization. But up to the present only a few polymers prepared by this method, which can't adapt the desire for diversification in structure and function of the conjugated polymers on the frontier of science and the high-technology. This thesis has developed the oxidative-coupling copolymerization method, which expanded the monomers for the reaction to coumarins, methoxynaphthalene, anthracene, pyridine N-oxide and so on, synthesized several new kinds of conjugated polymers, and studied the structure, characterization, especially the light emitting properties detailedly.The thesis is divided into 6 chapters.Chapter 1 mainly concerns three aspects. The first introduces the history of the conjugated polymers, the preparation of the familiar kinds of the conjugated polymers and the main application. The second introduces the basic knowledge of the organic electroluminescence, the background, development, the outlook of the PLED, and light emitting materials and devices. The third introduces the history of oxidative coupling polymerization, the reaction mechanism, and the evolution of oxidative coupling copolymerization. In light of the above introduction, the design strategies and contents ofIVthis thesis are outlined.In chapter 2, a novel kind of soluble copolymers incoporated anthracene and dialkyloxyl benzene moieties into main chain have been prepared by oxidative-coupling copolymerization. They were characterized by element analysis, FT-IR, 'H NMR, UV-Vis, GPC, X-ray, thermogrametric analysis, cyclic voltammetry and fluorescence spectrocopy. The link manners of anthracene and dialkyloxyl benzene in the copolymers were characterized by the model copolymers which contained 1,2,4,5-tetramethylbenzene. The copolymers are amorphous and show excellent solubility in common organic solvents, such as chloroform and THF. Thermogrametric analysis of the copolymers revealed that they have good stability with the onset decomposition temperature above 330. The electrochemical behaviors of the polymers were investigated by cyclic voltammetry. From the electrochemistry and absorbance spectroscopy, the HOMO and LUMO energy level of polymers were calculated. The doped conductivity of copolymers was investigated, and the conductivity was calculated. The fluorescence spectra of the copolymers in solid state film display blue light emitting properties with the maximum at 468nm, this behavior can be attributed to the "photo-harvest effect". The quantum yields of the copolymers were investigated, the quantum yields of the copolymers increase with the decreased anthracene content. The application of light conversion films of copolymers was studied, and the copolymers may be used in the light conversion films for agricultural.In chapter 3, the novel polymers inc...