Backbone structure conjugated systems

A 7i-conjugated systems is a molecule along the backbone of which occurs a continuous path of carbon atoms or heteroatoms, each carrying a p atomic orbital. The determination of the electronic structure of conjugated systems and their properties in terms of energy, electron and hole transport is very difficult. Electron correlation effects must be taken into account and the strong connection between, and mutual influence of, the electronic and geometric structures should be evaluated [91]. 

Electrically conducting polymers, sometimes called synthetic metals, have a backbone that is a rr-conjugated system, with alternating double and single bonds. This system is formed by overlap of carbon 2p -orbitals, as in Figure 7.17. The polymers are named after the monomer units on which their structures are based. The... 

All the components of a device are prepared with materials that can be chemically reactive. Metals constituting the cathode electrodes may react with the active layer causing a change in the structure of the conjugated system. Moreover, charge injection in polymers introduces reactive species in the backbone and creation of crosslinks between adjacent chains may not be excluded. 

The optical properties of CPEs are determined by the chemical and electronic structure of the IT-conjugated backbone. In general, the optical properties of a given CPE are similar to those of an organic soluble conjugated polymer that has the same backbone structure. However, important modifications in the properties of CPEs are often encountered due to the propensity of these materials to aggregate in solution. Examples of the absorption and emission properties of selected systems are described below. 

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