Doped and metallic polymers

3 This is characteristic of a metal and occurs because, in the presence of a magnetic field, the energy of spins parallel to the magnetic field is lowered and that of anti-parallel spins is raised. With a constant Fermi energy this means that anti-paraiiel spin electrons above F will flip their spins and occupy the empty parallel spin states below EF. There is then a preponderance of parallel spins that renders the metal paramagnetic. 

We will first consider how doping affects the properties in the semiconductor regime common to all conjugated polymers. 

The optical spectrum of PAc changes continuously during doping to 5-10 mass% of dopant, Fig. 9.31. The initial polymer contains a mixture of trans- and 

PAni has a very complex structure and doping behaviour, see Fig. 9.6, and the spectra are sensitive to the polymer morphology, the level of oxidation and degree of protonation. This accounts for the considerable variation in tire spectra that have appeared in the literature. The effects are illustrated in Fig. 9.33 for various forms of the protonated salt. These spectra refer to dried films, electrochemically prepared at different electrode potentials, and subject to oxidation by exposure to air. This variation in preparation conditions means that the degrees of oxidation and protonation are not well defined, as evidenced by the pronounced differences in the spectra of the emeraldine prepared at the 

Jarrett et al. (1995) have studied the relation between carrier mobility and conductivity in the semiconductor regime by studying the properties of FETs 

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