In-situ investigation of organic devices by using infrared spectroscopy and photoelectron analysis

在本研究中，我们结合光谱方法和电学测量对有机器件进行了研究。对于前者，我们采用了多重反射结构中的红外反射吸收光谱（MIR-IRAS）和光电子产额光谱（PYS），对于后者，我们采用了位移电流测量（DCM），并将DCM技术应用于各种有机器件，如有机晶体管、有机电致发光器件和有机电致发光器件。然后我们发现这种技术可以给我们有用的信息，载流子在有机器件中的行为，如载流子注入，积累，陷阱的数量，和积累的电荷的空间分布。在有机半导体方面，我们发现可见光照射对有机半导体的杂质掺杂有促进作用，并提出了一种新的掺杂方法--光诱导掺杂。对并五苯和聚噻吩薄膜的MIR-IRAS测量表明，光致掺杂的机理是通过光致电荷转移加速了主体有机半导体和客体杂质掺杂剂之间的电荷转移，我们研制了一套可在真空和大气条件下测量光电子产额谱的装置。由于用氮气净化UV单色光源的内部，因此可获得宽范围的光子能量（4- 9 eV）以覆盖大多数有机材料。我们还证明了PYS技术可以用来分析有机/金属界面的电子结构。在我们的建议下，最近，一家日本公司开发了一种用于测量OLED材料电离电位的商业仪器。

In this study, we have investigated organic devices by combing spectroscopic methods and electric measurement. As the former, infrared reflection absorption spectroscopy in the multiple reflection geometry (MIR-IRAS) and photoelelctron yield spectroscopy (PYS) were applied, and as the latter, displacement current measurement (DCM) was used.We have applied DCM technique to various organic devices such as organic transistor, organic electroluminescent devices, and organic bistable devices. Then we found that this technique can give us useful information about the behavior of carrier in organic devices such as carrier injection, accumulation, amount of traps, and spatial distribution of accumulated charge. Concerning organic transisotr, we found that impurity doping to organic semiconductor is enhanced by visible light illumination and proposed a new doping method of "photoinduced doping". MIR-IRAS measurement of pentacene and polythiophene film revealed that the mechanism of the photoinduced doping is the acceleration of charge transfer between host organic semiconductor and guest impurity dopant through photoinduced charge transfer.We developed an apparatus with which photoelectron yield spectroscopy can be measured both in vacuum and atmospheric conditions. Due to purging the inside of a UV monochromatic light source by nitrogen, a wide range of photon energy (4-9eV) is available to cover most organic materials. We also demonstrated that PYS technique can be used to analyze electronic structures of organic/metal interface. Under our advice, very recently, a commercial apparatus for measuring ionization potential of OLED materials have been developed by a Japanese company.