Growth and Purification of Phthalocyanine Polymorphs
The semiconducting properties of many organic compounds are measured with care taken to avoid spurious effects due to electroding and measuring methods, but often insufficient attention is paid to their state of chemical purity. Workers assume that extensive zone refining or sublimation procedures will yield high purity material neglecting to measure the nature, concentration and distribution of any remaining impurity. The crystal structure of the compound is, in the absence of a detailed X-ray analysis, sometimes inferred from other properties. If the organic compound can grow in different polymorphic forms under closely related growth conditions then such indirect methods can be open to misinterpretation. The aim of this discussion is to illustrate the foregoing by using as an example work carried out in our laboratory on the phthalocyanine (pc) series of compounds.
KeywordsPolymorphic Form alIa Film alIa Form High Purity Material Mica Substrate
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