Metal/conducting polymer junctions

In the sheathless interface, the electrical contact is obtained by coating with either a metal [85, 88-90] or a conductive polymer [91] the separation capillary outlet, which is shaped as sharp tip. Also employed are sheathless interfaces in which the electrical contact is established using a metal electrode or a conductive wire inserted into the outlet of the separation capillary [92], A small gap between the separation capillary and the needle of the ionization device filled by a liquid is the approach made to establish the electrical contact in the liquid junction interface [86,87], This arrangement is also realized by making porous through chemical etching the tip [93] or a small section of the wall [94] of the separation capillary at its outlet. 

The more traditional approach has already been used in anodic electrocrystallization processes to produce nanocompositions and superlattices of mixed Ti-Pb oxides [341-347]. With HTSC materials, initial steps have been made in this direction in studies on the electrochemical deposition of conductive polymers on the surface of microband YBCO electrodes [28,50,433]. In the resulting composition, the reversible transition from the HTSC/metal junction (at the high doping degree of the polymer) to the HTSC/semiconductor junction has been achieved. The properties of these compositions allow one to control the shift over a wide interval. 

It is certain that electrically conductive polymers have attracted much attention in the field of solid state science in recent years. They are expected to have convenient function in the production of useful electric or electronic devices such as the electrodes in rechargeable batteries, pn-junctions for use in integrated circuits (ICs) or in photovoltaic devices, and so on. In the normal sense, the organic polymers, even the 7r-conju-gated systems having mobile 7r electrons, are typical insulators of poor electrical conductivity and have been utilized as dielectric material. This is considered to be a result of the Peierls transition (Peierls, 1955), namely, a metallic-insulator transition, e.g., for polyacetylene, which is characteristic in the one-dimensional system. This situation is circumvented by the doping technique, in which the electron acceptors or donors... 

Rather little work has been reported on the use of conducting polymers in active semiconductor devices. A problem in organic pn-junctions is the interdiffusion of dopants destroying the abrupt interface. In Schottky junctions made of (the more stable) p-type polymers, metals with low work functions must be used. These metals, such as aluminium (work function 4 3 eV) are typically reactive and oxidize easily. 

It was shown that conducting polymer as the phase characterized with mixed conductivity exhibits metallic behavior in the open-circuit (identical to noble metals or carbon) in contact with the element (membrane, junction, solution) containing the redox pair, according to the Nemst equation ... 

These cells do not rely on a traditional p-n junction to separate photo-generated charge carriers. Polymer cell materials used include polyester (PET) foil, indium tin oxide (ITO) film, polyethylenedioxythiophene (PEDOT), and aluminum. Nanocrystalline cells use thin film materials and are overlayed on a supporting matrix of conductive polymer or mesoporous metal oxide. 

A number of functions require creation of p-n junctions. To date this is usually achieved with an ICP-metal, the metal being predeposited on a suitable substrate or sputter coated onto the polymer. Thin metal layers may also be necessary for highly conducting inter connects. More recently, p-n Junctions have been created using the same polymer with different dopants [152]. Alternatively, two different ICPs could be used. 

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