"In situ" measurement of phthalocyanine films in ultrahigh vacuum has been conducted in order to know the relationship between molecular orientation and electric properties in the condition without acceptor molecules. Elimination of adsorbed oxygen on AlPcCl molecules was not realized by heating the sample above 230°C in 2×10^-9 Torr. "In situ" measurement showed the thermal activation energy of 1.10eV for the oriented AlPcCl film (thickness: 200nm) which agreed with the optical absorption energy of the film measured in air. It is considered that AlPcCl film forms charge transfer complexes with oxygen remaining in the vacuum of 2×10^-9 Torr and gives E_g^CT=1.10eV.

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In this study, electric conduction of the organic EL device prepared from 8-quinolinol complexes as an emitting layer has been investigated. As the cathode metal with low work function gives the high luminous efficiency, the barrier between the cathode and the electron transport layer controls the electron injection from the cathode. Temperature dependence of current density is very weak and activation energy is independent of electrode materials. Electron injection under high electric field is well explained by tunneling theory. Hopping process is proposed as electron migration. Holes excessively injected from the anode accumulate in the interface between two organic layers and contribute to the enhancement of the electric field at the cathode.

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Plasma polymerization by using a pulsed rf discharge was performed for preparation of ultra thin organic film. The discharge capacitively coupled was initiated in a box-type reactor at an uniform flow of an acetylene/argon mixture gas. 2-10 nm scale ultra thin hydrocarbon film was deposited on a silicon wafer. The surface topography of the film examined by AFM appears to be pinhole free. The distribution of thickness measured by an elipsometer suggested the reaction in gas phase is significant. Therefore, the theoretical calculation was performed by using a model of radical reaction in the gas phase, and the obtained equations were fitted well to the results of experiments.

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The authors discussed the luminant properties of the organic electroluminescent diode (organic ELD) with multi layers and the conventional organic ELD with two layers (a hole transporting layer and an emitting layer) by means of the dye-doping method. For the organic ELD with five narrow, 5nm-thick emitting layers, the emission peak was shifted to the short wavelength region as compared with that of the conventional organic ELD. In addition, the FWHM of the EL spectrum was narrower than that in the conventional organic ELD. The emitting region in the organic ELD with multi layers was found to be a few emitting layers near the cathode, and not a few emitting layers near the anode side.
The shift of emission peak could be explained by the interference of a direct light and a reflected light onto the metal cathode mirror. But the decrease of FWHM could not be done by the interference effect. The decrease of FWHM was due to the suppression of EL with lower energy than the emission peak. The authors thought the following as the EL model: the ecitons which are generated in the TPD/Alq3 interface diffuse in the emitting layer. As the diffusing excitons lose their energy, these will come close to the ground state of excitons. In the organic ELD with multi layers, as the excitons cannot diffuse to more than the thickness of emitting layers, the component of EL with high energy relatively increases. Therefore, the FWHM of EL spectrum becomes narrow.

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Surface potential of heat-treated polyimide (PI) LB films deposited on Au, Cr, Al and ITO electrodes was measured in a dark vacuum vessel at various temperatures before and after photoirradiation. The surface potential depended on the electrode materials and the number of deposited layers. The surface potential saturated when the number of deposited layers was several tens. The saturated surface potential was a linear function of the work function of electrodes at temperatures between-100°C and 150°C before photoirradiation, and at room temperature after photoillumination. It was suggested that excess charges were transferred from metal-electrodes into PI LB films until the thermodynamic equilibrium was established at the interface. We also measured the surface potential of 4kinds of polyimide LB films. The potential of polyimide with electron accepters changed negatively, and the potential of polyimide with electron donors changed positively with the increment of temperature. In contrast, the potential of polyimide with electron accepters changed positively, and the potential of polyimide with electron donors changed negatively with photoirradiation.

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Experimental studies of the fabrications of polymer and non-polymer organic thin films by laser ablation are discussed. We succeeded in fabrication of crystalline thin films of polytetrafluoroethylene (PTFE) by F₂ laser (157nm) ablation. As an example of the application of the PTFE thin film, we fabricated PTFE thin films containing semiconductor CdTe microcrystallites, which show a 3rd-order optical nonlinearity. Non-polymer organic thin films fabricated by KrF laser (248nm) ablation, such as copper-phthalocyanine (CuPc) and 4-dialkylamino-4'-nitrostilbene (DANS), also showed crystallinity and little change in their composition when reducing the laser ablation fluence close to the ablation threshold fluence of -20mJ/cm².

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Displacement current across multilayer films of lipid membranes was measured with thermal stimulation and the critical temperature of membrane films due to phase transition from ordered gel to disordered fluid was determined. The membranes used here were L-α-Dilauroyl, Phosphatidylcholine (DLPC) and L-α-Dimyristoyl, Phosphatidylcholine (DMPC). The phase transition temperatures of DLPC and DMPC were determined 43°C and 78°C, respectively.

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Structure and optical properties for LB ultrathin films of spiropyran (SP) dyes have been investigated using the attenuated total reflection (ATR) method, which resonantly excites surface plasmon at an interface between metal and dielectrics. SP dyes change from SP to photomerocyanine (PMC) forms by UV irradiation, and visible irradiation or heat treatment causes the reverse change. The LB ultrathin films, which consisted of the mixtures of SP, arachidic acid (C20) and octadecane (HC 18), were deposited on Ag thin films in the dark. The ATR properties due to the change of the molar ratios of the mixtures were observed, and showed that the SP LB films containing HC18 had the highly ordered structure. The ATR for the SP LB films with HC18 exhibited the reversible changes by the photoisomerization. The structure and the optical properties of the SP LB films changed with the temperatures of the heat treatment, and the ATR properties corresponding to the heat treatment were also observed.

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Multilayer heterostructure thin films of electroactive polymers such as poly (p-phenylene vinylene), PPV, precursor and sulfonated polyaniline, SPAn, have been successfully fabricated via process based on the spontaneous self-assembly of conjugated polyion on a substrate. We have prepared SPAnIPPV multilayer heterostructures light-emitting diodes (LEDs) using this electrostatic self-assembly technique and discussed the electroluminescent (EL) properties. The SPAnIPPV monolayer LED emits greenish-yellow light, but SPAnIPPV multilayer LED emits bluish-green light and there is a slight shift between the two spectra of these devices. These results can be interpreted in terms of the confinement effect of carriers in the superlattice structure consisting of SPAnIPPV multilayer system.

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Spiropyran LB films were prepared by adding arachidic acid and n-oct adecane. We investig ated the relations among the film preparation condition, the film structure and the optical properties such as UV absorption and degree of isomerization. The structure of spiropyran LB film was successfully controlled by adding proper amount of arachidic acid and n-oct adecane. These films showed stable and reversible photo is omerization.

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Optical properties of Arachidic Acid (C20) Langmuir-Blodgett (LB) films adsorbing crystal violet (CV) dyes were investigated and the structure of the C20CV LB films was estimated. The electrical properties were also studied. The polarized reflection spectra showed an absorption band of the Langmuir films perpendicular to the water surface under high surface pressure. In the C20CV LB films, the absorption band was more clearly observed. The absorption band due to brick stone work arrengements of CV molecules were calculated using an extended dipolar model, and the orientation of CV molecules was estimated. In UV- irradiated C20CV LB films, leuco-compounds of CV were also observed. From the current vs. voltage and thermally stimulated current (TSC) measurements, it was found that the currents for the C20CV LB films containing CV dyes became larger than those for C20Cd LB films. The conduction mechanism and TSC of UV-irradiated C20CV LB films also changed and the changes were thought to be caused by the leuco-compounds of CV.

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Inelastic electron tunneling spectroscopy (IETS) has been used for the investigation of vibronic excitationof molecules in organic thin layer. This technique has commonly utilized tunnel junctions fabricated in theform of a metal/metal oxide/metal structure. However, this structure has some difficulties because tunnelingcurrent strongly depends on the fabrication methods of the metal oxide. We used highly doped siliconsubstrate with a thin SiO₂ film which provided good tunneling barriers by using a standard semiconductorproccessing technique.
In this paper, IET spectra of MIM and MIS structure have been calculated to investigate the effect of siliconsubstrate on IETS measurment. We have also disscussed the results obtained by the calculation in comparisonwith experimental IET spectra.

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