Experimental Studies on the Structure and Interfacial Electronic Structure of Organic Ultrathin Films on Inorganic Solid Surfaces

近年来，无机固体表面有机薄膜的结构和功能性受到了广泛关注，与分子器件和液晶显示器件等各种应用有关。这种功能的很大一部分取决于在非常界面处的薄膜的结构，并且界面电子结构对于电子功能是重要的。人们对这种薄膜的结构和分子取向进行了研究。另一方面，界面电子结构的研究主要是通过宏观测量，如电流-电压特性。本文建立了一种利用紫外光电子能谱（UPS）直接测定界面电子结构的新装置，并辅以Penning电离电子能谱（PIES）等辅助技术。利用该装置和分子科学研究所的UPS同步辐射系统，我们测定了几种电子学上感兴趣的有机固体和界面的电子结构。所研究的系统包括：聚硅烷和聚锗烷、硅立方烷、氨基喹啉、对六苯基、聚吡啶、聚（联吡啶）、部花菁染料和卤化银之间的界面、以及卟啉和金属（Au、Ag、Cu和Al）之间的界面。染料/银界面的研究与染料的实际增感行为具有良好的相关性，有力地支持了染料光谱增感的电子转移机理。卟啉/金属界面的研究结果对传统的简单模型提出了质疑，指出了更广泛地研究有机/无机界面的重要性。

Recently, there has been much attention on the structure and functionality of organic ultrathin films on the surface of inorganic solidsk, in relation to various applications such as molecular devices and liquid crystal display devices. Much part of such functions depend on the structure of the thin films at the very interface, and the interfacial electronic structure is important for the electronic functions. There have been studies of structure and moleculra orientation of such films. On the other hand, the interfacial electronic structures have been mostly studied only through macroscopic measurements such as current-voltage characteristics. In this work, we constructed a new apparatus for directly determining the interfacial electronic structures by UV photoemission spectroscopy (UPS), with auxiliary techniuqes for estimating the structures such as Penning ionization electron spetroscopy (PIES). Measurements with this apparatus and also with the UPS system at Institute for Molecular Science using synchrotron radiation, we determined the electronic structures of several eletronically interesting organic solids and interfaces. The systems studied include : polysilanes and polygermanes, silacubane, alminoquinoline, p-sexiphenyl, polypyridine, poly (bipyridine), interfaces between merocyaine dyes and silver halides, and interfaces between porphyrins and metals (Au, Ag, Cu, and Al). The study of dye/silver halide interfaces showed excellent correlation with the actual sensitizing behavior of dyes, strongly supporting the electron transfer mechanism of spectral sensitization by dyes. The results of porphyrin/metal interfaces cast doubt on the traditional simple models, pointing out the importance of more extensive studies of organic/inorganic interfaces.