报告人：Professor Hironobu Hayashi
Nara Institute of Science and Technology (Japan)
摘要：Large aromatic molecules such as large acenes and polycyclic aromatic hydrocarbons are regarded as promising materials for organic electronic devices. However, it is normally difficult to synthesize such large aromatic molecules because of the low solubility and stability. On the other hands, we have developed thermal and photochemical precursor methods to overcome these problems. Briefly, bicyclo[2.2.2]octadiene(BCOD)-fused acenes can be converted to the corresponding acenes by the thermally induced retro-Diels-Alder reaction, while a–diketone–type precursors can be converted simply by photoirradiation . Specifically, irradiation of a–diketone–type precursors at the n–p* absorption leads to the release of two molecules of CO, and the corresponding acenes can be prepared quantitatively in solutions or in films. Importantly, these precursor molecules are often more soluble and stable than the corresponding one.Here, by using the precursor method and on-surface synthesis under ultrahigh vacuum (UHV) conditions, we have successfully synthesized heptacene and nonacene on Au(111) to provide experimental insight into the chemical and electronic structure. Through combined scanning tunneling microscopy/spectroscopy and non-contact atomic force microscopy measurements, together with state-of-the-art first principles calculations, HOMO-LUMO gaps of these large acenes were experimentally revealed .
Resume：Hironobu Hayashi received his Ph.D. degree in 2012 from Kyoto University (Japan) under the supervision of Prof. Hiroshi Imahori. He spent 2012–2014 as a postdoctoral fellow with Prof. Stefan Matile at Geneva University (Switzerland). In 2014, he joined the Division of Materials Science at Nara Institute of Science and Technology (NAIST) in Japan as an Assistant Professor (Prof. Hiroko Yamada group). His research focus on synthesis of functional aromatic compounds, fabrication and evaluation of dye-sensitized solar cells, self-assembly of organic/inorganic materials, surface chemistry. He has published more than 50 papers with the citation number over 1293.