Pyrene Functionalized Optical Materials Design, Synthesis And Applications

With the development of information technology, more emphasis is paid to information display technology. Flat panel displays and soft displays come to be the future display terminals. Since 1990s, organic light emitting diodes (OLEDs) have come to be the promising candidate for future display technology. OLED device has many advantages such as light weight, thin, fast response, low energy cost, large display angle and could be manufactured on soft matrix. These advantages attracted huge attention from both academics and industry. In the following decades, OLEDs developed in fast pace both in materials and device technology. From device perspective, multilayered device, spin-coated device are fabricated and the interface engineering is intensively studied. For materials, many brand new electrochromophores are developed which gradually increase the efficiency. The correlation between function and structure gradually established. OLED is a basic research area which also project high utilitarian roles. Besides the advancement of increasing efficiencies, the structure-function relationship gives new light to organic semiconductors. In device engineering, a lot of important technologies are developed, such as device interlayer engineering and paste cathode.This thesis devoted to observe the structure-function relationship from material's perspective. The main research topic is high band gap organic semiconductors, in which fluorene derivatives prospers for their high fluorescent quantum yields and good thermal stability. The oligomers and polymers of fluorene derivatives have good film forming ability and could be used in solution processed device technology such as spin-coating and jet-printing. Besides, fluorene could be modified chemically in many aspects to turn their electronic structure and enhance their performance. The other important segment in our materials design is pyrene. Pyrene is a polyaromatichydrocarbone which has good quantum yields and deep blue emission and is widely used in biotechnology. Besides, it has high carrier mobility and could reduce the hole-injection barrier from anode. These points make it promising optoelectronic materials. Compared to anthrancene, the research of pyrene in optoelectronic lags far behind and in this thesis we devoted to explore its optoelectronic utility. We designed and synthesized three series of pyrene functioned materials. Their chemical and physical properties, electronic structure as well as device function are studied.In the first chapter, we reviewed the development of linear polyfluorenes, fluorene copolymers, hyperbranched polyfluorenes, dendritic and starburst materials, vacuum deposited small molecules as well as spin-coated small molecules. These categories of materials have their unique properties, and we basically conclude their structure-function relationships. In the literature survey, we conclude the material design protocol and highlighted several interesting research topic. At last we forward our design clue and the main research project.In the second chapter, we summarized all the characterization methods and the chemicals used. We also paid a little attention to device fabrication as well as basic knowledge of quantum chemistry.In chapter three, we concentrated on pyrene functioned spirocompounds. 9,9-diarylspirobifluorene is a famous building block in optoelectronic materials. They have good thermal and morphological stabilities. We first developed a synthetic approach towards a new family of spirocompounds. In the following work, we use pyrene to function the spiro-building blocks. In the last, we use the synthetic technology to control the spiro segments of fluorenes. Different sized spirofluorenes are produced. Their pyrene function molecules are also studied.In chapter four, we use pyrene to modify the C9 position of fluorene and synthesized 9,9-diarylfluorene. Then the 2,7 positions of fluorene are functioned by pyrene, thus the blue emitters are produced. When we introduce enthylpyrenyl group to the 2,7 position of fluorene, the resulted materials show blue emission in solution and green emission in film. The most interesting point of these molecules is that they could form smooth film by spin-coating. DuPont announced their development in small molecular solution process technology in 2006, and we sincerely hope our development could make some contribution to this fast developing technology.In chapter five, we use pyrene as the functional core to construct starburst conjugated molecules. Starburst material is a new highlighted topic in optoelectronic in recent years, many brand new molecules are developed which add many chemistry to OLEDs. Yet their structure-relationship is still blurred. We studied our pyrene starbursts from device engineering as well as their electronic structure. By adding some investigation of their chemical and physical properties, their basic structure-property relationship is summarized. In the last, we use quantum chemistry technique to study different substituted pyrene to anaylsis substitution effect on optoelectronic properties of pyrene starburst.