What Is the Conducting Zone?

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The conductivity of the conductor and insulator multiphase ceramics is in accordance with the theory of percolation. The percolation transition curve is affected by many factors. In addition to the ratio of the two phases of the conductive phase and the insulating phase, the size, shape and distribution of the two-phase particles The influence of the firing temperature and temperature system of the multi-phase ceramics on the critical index, the grain size ratio and the grain boundary layer, and thus the percolation transition curve.

Conductor-insulator composites have been a widely studied subject. Various factors (geometric factors and electrical characteristics of each phase) in a conductor-insulator composite determine its macroscopic electrical properties. The influence of each factor on the properties of the composite is extremely important. ^[1]

Organic compounds also conduct electricity

For a long time, in terms of electrical conductivity, people have often been used to treating organic compounds as insulators. But this is not exactly the case. With the development of polymer chemistry and synthetic technology, the mechanism of electronic conductance of solid organic compounds has been well understood. Graphite used as a conductor in industry is actually a typical organic polymer compound with metal conductive properties.

An outstanding feature of organic compounds, especially polymer compounds, is that by virtue of certain known relationships between their molecular hooks and properties, their various properties can be adjusted through the synthesis of macromolecules. Although graphite has good electrical conductivity, its mechanical properties and processing properties are poor, which limits its application range. Therefore, if an organic conductor with good mechanical and processing properties can be created, it can play its role in a wide range. ^[2]

Electronic Conduction Mechanism of Molecular Solids

In order for an organic compound solid to be as conductive as a metal, we must first understand what kind of solid it is and what are the main differences between it and metal in terms of basic structure? From a crystallographic point of view, metals are atomic crystals, and organic compounds It is a molecular crystal. In fact, only organic low-molecular compounds are molecular crystals. As for organic polymers, it is often difficult to make single crystals. In addition to the crystalline phase, there is an amorphous phase in the solid. The existence of amorphous phase in organic materials can make it have good mechanical properties and processing properties, so organic conductors can only be regarded as molecular solids. When analyzing its electronic conductivity characteristics, it must take into account the existence of amorphous phase. ^[2]

Metals conduct electricity because there are free electrons in their atomic crystals that conduct electricity. There is no such free electron in molecular solids. To make it conductive, we must first rely on special molecular structure design to provide appropriate carriers (electrons and holes). Secondly, the accumulation of molecules and particles in the solids is controlled by Van der Waals forces. The distance between the molecules is large, and the overlap of the electron cloud is very poor. Even if there is already in the molecule, it can move under an external electric field It is also more difficult for a carrier to migrate from one molecule to another, and it must be activated to cross the molecular barrier. This is why organic compounds are mostly insulators. Therefore, in order for an organic compound to become a conductor, its molecular structure must have at least the following two conditions: (1) to be able to generate carriers, and (2) the electron clouds between the molecules to have a certain degree of overlap. ^[2]

Ways to improve conductivity

In order for the organic conductor to exhibit metal conductivity, and to maximize its electrical conductivity, improving the geometrical factors of the crystal structure becomes a particularly important issue. Its specific content is: how can we control the geometric packing of molecules in the crystal? How can the donor and acceptor form their own molecular pillars? How can there be an equal molecular plane spacing in the molecular pillars? How can I maintain an effective crystal structure at low temperatures? It does not change so that it does not change from an organometallic back to a semiconductor? But the basic principle is clear: these factors depend on the interaction between molecules. To control this interaction force, only the calculation based on the existing theoretical basis can be used to design a more effective molecular structure of the organic conductor and further improve the conductivity. ^[2]

Prospects for widespread application of organic conductors

In order for organic conductors to be used in a wide range of industrial sectors, in addition to further improving their electrical conductivity, attention must also be paid to their mechanical and processing properties. Therefore, some or all of the components of the organic conductor must be polymer compounds. The most ideal design is that molecules in the crystalline region can provide metal conductance, while molecules in the amorphous region provide toughness and processability. After the organic conductor is processed and formed, a post-treatment may be performed to further improve the crystalline region and improve the conductivity.

Organic conductors are new materials inspired by the molecular structure of graphite. In the past, research and development mainly focused on retaining and improving the electrical conductivity of graphite, but to overcome its shortcomings of poor mechanical properties and processability. The prospect of the widespread application of organic conductors in industry is promising. In addition to the expectation that it can replace metal copper in the electronics industry and even in the power industry, there is even the possibility of developing organic superconductors. ^[2]