Conducting Mechanisms - Conductivity in Inorganic Semiconductors
• The nature of the processes that induce high conductivity in polymers is different from those
inorganic semiconductors. In the doping of inorganic semiconductors such as silicon, the
species occupies positions within the lattice of the host material, resulting in the formation o
electron rich or electron-deficient sites with no charge transfer occurring between the sites.
• The doping reaction in polymers, on the other hand, is a charge-transfer reaction, resulting in the
oxidation or reduction of the polymer, rather than the creation of holes.
, Conducting Mechanisms - Conductivity in Inorganic Semiconductors
The doping process in the case of conducting polymers may therefore be more
correctly classified as redox processes of the following general scheme
• The exposure of polyacetylene to an oxidizing agent X (or reducing agent M) leads to the formation of a
positively (or negatively) charged polymeric complex and of a counterion which is the reduced X- (or the
oxidized M+) form of the oxidant (or the reductant).
• The doping process in the case of conducting polymers classified as redox process
Polymer + X = (polymer)n+ + Xn --
Where X = I2, Br2, AsF5 in the case of an oxidation
Polymer + M = (polymer)n-- + Mn +
Where M= Na, Li in the case of reduction
• The above reactions are most likely to occur in the case of unsaturated polymers with π electrons as they
be easily removed from the polymeric chains to form polycations or added to the chains to form polyanion
• The nature of the processes that induce high conductivity in polymers is different from those
inorganic semiconductors. In the doping of inorganic semiconductors such as silicon, the
species occupies positions within the lattice of the host material, resulting in the formation o
electron rich or electron-deficient sites with no charge transfer occurring between the sites.
• The doping reaction in polymers, on the other hand, is a charge-transfer reaction, resulting in the
oxidation or reduction of the polymer, rather than the creation of holes.
, Conducting Mechanisms - Conductivity in Inorganic Semiconductors
The doping process in the case of conducting polymers may therefore be more
correctly classified as redox processes of the following general scheme
• The exposure of polyacetylene to an oxidizing agent X (or reducing agent M) leads to the formation of a
positively (or negatively) charged polymeric complex and of a counterion which is the reduced X- (or the
oxidized M+) form of the oxidant (or the reductant).
• The doping process in the case of conducting polymers classified as redox process
Polymer + X = (polymer)n+ + Xn --
Where X = I2, Br2, AsF5 in the case of an oxidation
Polymer + M = (polymer)n-- + Mn +
Where M= Na, Li in the case of reduction
• The above reactions are most likely to occur in the case of unsaturated polymers with π electrons as they
be easily removed from the polymeric chains to form polycations or added to the chains to form polyanion
