Barrier Properties of Printed Composite Zinc Phthalocyanine/Fullerene Sandwiched between Indium Tin Oxide and Alluminium Electrodes

Abstract

TO/ZnPcSu-PCBM/Al heterostructure was prepared by ink-printing and studied by DC (current-voltage characteristics) and AC (dielectric spectroscopy) techniques (ZnPcSu means 3-diethylamino-1-propylsulphonamide substituted Zn phthalocyanine, PCBM phenyl-C61-butyric acid-methylester fullerene). At the Al contact a Schottky barrier was formed. To explain the shape of current-voltage characteristic two effects had to be taken into account, emission effect, overcoming the potential barrier effect, formed by the superposition of the image Coulombic, space-charge and external potentials, by charge carrier. Dielectric spectroscopy made possible to determine effective lifetime of charge carriers and characteristic time related to electron diffusion; lifetime of charge carriers was τd = 2.10-5 s, and the electron mobility was of order 104 cm2V-1s-1.