Polymers with Conjugated Bonds, Heteroatoms and Heterocycles in the Backbone Chain

4 Polymers with Conjugated Bonds, Heteroatoms and Heterocycles in the Backbone Chain 

Another important step was made by Wegner who obtained crystalline polydiacetylenes of high molecular weight exhibiting a fully conjugated backbone [113]. The theory describes the electron structure of the polydiacetylenes in the frame of the ID wideband semiconductor. The polydiacetylene systems are 

Now the research in the photoconductive properties of the polyconjugated materials is growing fast. Heterocycle or heteroatom-containing polymers are involved in this process due to their excellent mechanical and electric properties. The sensitized photoeffect in polyconjugated materials was first observed in 1964 [19,20] and the high significance of the increase in the photosensitivity of these compounds became apparent 

Commonly, the increase in the conjugation chain length leads to the bathochromic shift of the absorption bands. The optical and photoelectrical properties analysis needs to take into account not only formal polyconjugation following from the molecule chemical structure but effective conjugation defined by sterical factors too. 

The numerous defects inherent in organic polymers creates the donor or acceptor impurity levels. The low drift mobilities of the order 10-7-10-12 m2 V-1 s 1 lead to the paradoxical situation where the length of the free travel distance for the charge carrier becomes less than the size of the separate molecule links. So the hopping or activated models are the most acceptable ones for polymers in such circumstances. 

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