CHARATRETIZATION OF FLEXIBLE NANO INTERFACIAL FILM BY MEANS OF MAXWELL DISPLACEMENT CURRENT AND OPTICAL SECOND HARMONIC GENERATION

本研究的目的是通过麦克斯韦位移电流(MDC)和光学二次谐波(SHG)测量来表征有机单层膜的线性和非线性介电性质。宏观介电性质，如线性和非线性介电常数，与组成分子的取向有序参数密切相关。从这个角度来看，本研究是在研究人员提出的MDC测量和倍频测量相结合的思想的基础上进行的。(1)将界面单分子膜作为一个柔性系统来处理。界面的存在限制了分子的方向，从而诱发了自发极化和非线性极化等特殊极化。我们研究了这种极化，以评估系统的灵活性。我们可以找到薄膜的柔性与其电学性质之间的关系。(2)我们使用了棒状液晶分子、生物分子、手性螺旋分子和光异构体。形成了这些分子的朗缪尔单分子膜，并测量了它们的MDC和SHG。根据MDC和倍频测量的结果，我们可以揭示单分子膜的几何结构和电子结构。对于有机器件，如有机场效应晶体管和有机电致发光器件，我们提出了评估器件中电场分布和探测器件中载流子运动的新技术。在麦克斯韦-瓦格纳分析的基础上，提出了描述有机场效应晶体管工作过程的模型。

The purpose of this investigation was to characterize the linear and nonlinear dielectric properties of organic monolayer films by means of Maxwell-displacement current (MDC) and optical Second Harmonics Generation (SHG) measurement. The macroscopic dielectric properties such as linear and nonlinear dielectric constants are strongly related to the orientational order parameters of the constituent molecules. From this point of view, this investigation has been carried out on the basis of the idea of MDC measurement coupled with SHG measurement, proposed by the investigators.(1)Interfacial monolayer was treated as a flexible system. Direction of molecules is restricted by the presence of interface, and thus the specific polarizations such as spontaneous polarization and nonlinear polarization are induced. We investigate such polarization to evaluate the flexibility of the system. We can find the relationship between flexibility of films and the electrical property of them.(2)We used rod-like liquid crystalline molecules, biological molecules, chiral helix molecules and photo-isomers. Langmuir monolayers of these molecules were formed and measure the MDC and SHG. According to the result obtained from the MDC and SHG measurement, we can reveal the geometrical and electronic structure of monolayers. In particular, we successfully reproduce the pattern formation of molecular domains on a water surface.(3)For organic devices, such as organic field effect transistor and organic electro luminescent devices, we propose novel techniques for evaluating the electric field distribution in the devices and for probing the carrier motion in the devices. Also, we proposed a model which describes the operation of the organic field effect transistors on the basis of Maxwell-Wagner analysis.