Studies On The Synthesis And Structure Of The Organic Semiconductor Materials

The study and application of organic semiconducting materials in modern opto-electronics have attacted extensive attention from research communities and industry, due to their unique advantages of light-weight, transparency, mass production and high performance. Decades investigations in developing novel OSMs to meet the adverse requirements from different devices have led to plenthory of semiconducting materials. Moreover, the synthetic strategy toward materials with certain chemical structures are of importance and in great demand for particular attention.In this regard, we proposed my master thesis focusing on the synthesis and physical properties of semiconductors based on quinoxaline(Q) unit. The quinoxaline is a derivatives o-benzodiazmine with strong electron-withdrawing properties, which has been used as building blocks in many organic/conjugated polymer systems to achieve materials with tuned energy level alignment and bandgaps. In many cases, the studies on Q are involved the substituents of alkyl chaines and their conjugation fashion in conjugated backbones. And, few of reports showed narrow-bandgap small molecules based on Q units. Therefore, two quinoxaline-based small molecule materials, BDTQ X-O and BDTQX-T was designed and synthesized for the applications in organic photovoltaics.To synthesis of BDTQX-O and BDTQX-T, a straightforward synthetic strategy involving two consequent Stille coupling was adopted. Interestingly, the high efficiency Stille coupling reaction works not very well in our hands, which always gave a series of by-products. After carefully designation, we confirmed that three major side reactions took placed in the Stille coupling catalyzing cycle. These results of great importance in guiding the organic semiconducting mateirals design and synthesis, especially the regioregularity of conjugated polymer which obtained through the Stille condensation with high molecular weight.In addition, most of the research in organic electronics are focusing on the performance of devices and the chemical structures of OSMs. It is also importance to see in depth of the materials physical chemistry, especially the weak interaction among the condensed molecules, for example, Von de Walls and π-π interaction. Thus, we designed a series of naphthalene tetracarboxylic anhydride base conjugated systems with specific alkyl chains. It was expected that the alkyl chains can impart great influence on their molecular packing modes and microphase in co ndensed phase. Preliminarily, the alkyl chains with liquid crystal phase will show more complicated influence on their thermal induced phase-transistion.In summary, we achieved foundamental results in the synthesis of organic semiconductors and insight view in the morphology of organic semiconductors containing polycyclic aromatics.