Electronic Phenomena at the Hetero-Nanointerface Fabricated from Self-Assembled Films and Photoelectric Conversion Devices

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Recently, research into the practical use of organic materials in electronic devices has produced excellent results. It is considered that conducting polymers with highly extended π-electron conjugated systems in their main chains are highly promising materials for organic electronic devices. Because interfaces consisting of condicting polymer/metal or conducting polymer/conducting polymer are necessary in polymer electronic devices, the electronic phenomenon at the interface is critically important to the performance and the function of such devices. The fundamental device properties are affected by interfacial properties. Accordingly, it is necessary to understand not only the properties of the conducting polymer itself, but also interfacial electronic phenomena and electronic states on a nanometer scale.A novel thin film processing technique has been developed for the fabrication of ultrathin films of conducting polymers with molecular level control over thickness and multilayer arc … More hitecture. This new self-assebly process opens up vast possibilities in applications which require large area ultrathin films of conducting polymers and more importantly in applications that can take advantage of the unique interactions achievable in the complex, supermolecular architectures of multilayer films.Photoirradiation effects of a polypyridine, PPy/poly(2-methoxy-5-dodecylozy-p-phenylene vinylene), MDOPPV heterostructure photoelectric conversion device have been investigated. The photovoltaic characteristics of the heterostructure photoelectric conversion device are considerably improved from those in single-layer photoelectric conversion device are considerably improved from those in single-layer photoelectric conversion devices. Quenching of photoluminescence both in the PPy layer film and in the MDOPPV layer film has also been observed in the PPy/MDOPPY heterostructure film. The observed photoirrsdiation effects of the heterostructure device indicate that a photoinduced charge transfer occurs between PPy and MDOPPV. However, the photoinduced charge transfer between these polymers cannot be explained by the bulk electronic energy states of the polymers. A possible mechanism, which takes modulation of electronic energy states at the interface due to a local lattice distortion into account, has been proposed.The electronic state at the conducting polymer/electrode interface in air was investigated. The Fermi level (E_F) as well as the ionization potential (Ip) at the surface of conducting polymer films coated on various substrates was observed as a function of film thickness. The E_f of the conducting polymer surface was estimated by Kelvin probe method, and the Ip was estimated by atmospheric photoelectron spectroscopy. When Al was used as the electrode material, the dependence of the EF on film thickness was much different from that of the Ip. Less