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  1. As we already know, an electric current is a flow of electric charges which are, in the area we are discussing, carried by electrons. 



    Thus, electric current in conductive materials is the flow of electrons from atom to atom. 


    How electrons are held in the atom structure determines the conductivity of the material. In metallic atom, electrons are held loosely, meaning that they can move freely in the matter. Meanwhile, in non-metallic materials, outer electrons are held very closely to nucleus, result in very little or no conductivity


  2. Non-metallic material being discussed in this case, is conductive polymers. 

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    As we already know polymers (e.g.  plastics) as long chain of repeating unit of monomer. There are two factors which make a certain type of polymer a conductive polymer:

    1. The polymer must consist of in alternating single and conjugated double bonds. 

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      This structure can be found in for example: polyacetylene, polyaniline, polypyrrole, etc… The key here is the conjugated double bond, also known as the π bond. 
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      While the single bond (or ∑ bond) holds the atom together by concentrating the electrons between atoms, the π bond strength the connection between atoms by attracting electrons above and below the molecules. 

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      This strengthening create the basis for electricity current introduced in the second factor.

    2. The other crucial factor is doping. While doping can help create semiconductor materials from already conductive metallic materials, it also help enhance the conductivity of polymers. 

                                     

      Doping can remove electrons from the outer space of the atoms, allowing the remaining electrons of the current orbital to freely move. Doping can also add electrons to force the atom to create another orbital, in which the new electrons is now the “remaining” of the new orbital can also move freely. 


  3. Technically, conductive polymers can be applied in all the use cases of conventional metallic materials. While metal mining, processing, and shipping can be expensive, conductive polymer is the most attractive alternative at the moment, because they are light, cheap, and easily made flexible. 

    However, researchers have yet to find a large-scale, consistent and environmental friendly method to process and create conductive polymers. Currently industrial applications of conductive polymers are:

    1. Organic transistors

    2. Organic LED

    3. In flat panel display

    4. Organic solar cells

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