Phthalocyanine thin films semiconductor characteristics

From a number of studies at thin films of unsubstituted phthalocyanines which have been reviewed earlier " ", it has become clear that the films behave as semiconductors. The photoconductivity generally observed for films of phthalocyanines clearly showed the possibility to dissociate excitons into mobile carriers. Under most conditions films of unsubstituted phthalocyanines were found to be partly oxidized and hence showed p-type characteristics. This was seen from measurements of the electrical conduction, the thermopower established by a temperature gradient across a sample, and by the rectifying characteristics injunctions. A generally quite low mobility of about lO -lO" cm s was found for the electron vacancies in phthalocyanines, barely allowing the applicability of a band model which dwells upon the assumption of delocalized... 

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