Epitaxy as a Means to Generate Oriented Opto- or Electroactive Materials

4 Epitaxy as a Means to Generate Oriented Opto- or Electroactive Materials 

In the present context, we report only on the elucidation of the epitaxy and its analysis and, in a second part, on the development of elaboration conditions that help produce large size oriented systems. 

Unsubstituted conjugated polymers such as polythiophene and poly(para-phenylene) cannot be processed in the form of thin films. One means to overcome this difficulty is to use oligomers since they share frequently the properties of their higher molecular weight counterparts (e.g., the electroluminescence of para-sexiphenyl [PSP] and poly(para-phenylene)). The oligomers are easier to process and, in the context of this chapter, can be oriented by epitaxial crystallization. Deposition techniques are very varied. For PSP, various processing conditions are available molecular beam epitaxy, hot wall 

Epitaxial crystallization is one of the few methods that make it possible to control by nonmechanical means and under appropriate processing conditions the morphology and/or structure of crystalline polymers. Furthermore, it may generate single crystalline, although multilamellar, polymer morphologies. 

The rules governing epitaxial crystallization had been set up early on for low molecular weight materials. By and large, the same basic rules apply for polymers. However, the structural and conformational diversity of crystalline polymers, and their lamellar structure introduce new and subtle variables in the process. 

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