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

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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.