The Concept of Doping as Applied to Conjugated Polymers

The partial oxidation of conjugated polymers is generally referred to as p-doping, again in analogy to other semiconductor materials, but the basic process is the removal of electrons as in any other branch of chemistry, i.e., 

Similarly n-doping is a partial reduction of the polymeric material, i.e., 

These processes can be made to occur in a number of ways, for example with gas phase reagents such as AsF5 and I2, solution species such as FeCl3 or using electrochemical oxidation and reduction, but regardless of the method used the basic process is the same. If the material is to maintain overall electrical neutrality during and after doping, a counter ion is required, i.e., for p-doped materials, 

It is a convenient aspect of electrochemical doping of the polymer that the electrolyte can provide the counter ion, although a similar result can be achieved via chemical doping under certain circumstances, e.g., Using a radical ion containing species such as sodium naphthalide, Na+ npthT, i.e., 

A similar result can also be achieved by using an alkali metal in an amalgam, where the metal serves both to reduce the polymer and to provide the counter ion, i.e., 

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