Conducting polymers

A survey is presented of the progress made in recent years in the field of conducting polymers. This includes progress (i) on the experimental side (preparation, characterisation and doping, (ii) in the theoretical description of quasi-one-dimensional systems, (iii) in technological applications of linearly conjugated polymers. The advantages and disadvantages of each material are compared and contrasted. Most of the impetus for the current research in this area was provided by the discovery of the highly conducting properties of the doped polyacetylenes. The physical, chemical and structural properties of the polyacetylenes and substituted polyacetylenes are therefore discussed in greater detail. In its idealised form trans-polyacetylenes can be described as a Peierls semiconductor. This then leads to new and exciting concepts including elementary excitations known as solitons and polarons. Solitons will, for example, exhibit unusual charge-spin relationships. We argue however that the inseparability of structural and electronic configuration is not peculiar to polyacetylene but common to most linearly conjugated quasi-one dimensional materials. The physical decription of linearly conjugated quasi-one-dimensional materials is therefore compared to those of conventional semiconductors. Finally a brief outlook is given on future research and possible device applications.