Drift mobility, trapping and photogeneration of charge carriers in β-metal-free phthalocyanine single crystals

Abstract

By means of a pulsed photoconductivity technique using a Q-switched ruby laser, drift mobilities of electrons and holes at temperatures between 290 K and 600 K have been measured in beta -metal-free phthalocyanine single crystals. At 373 K, the mobilities of electrons and holes are respectively mu e approximately=1.2 cm2V-1s-1 and mu h approximately=1.1 cm2V-1s-1 for carrier motion in the c' direction. The temperature dependence of the mobility of both types of carriers can be expressed in the form mu alpha T-n, where 1.3<n<1.6 for electrons and 1.1<n<1.6 for holes. The electron trapping time tau e approximately=2*10-6s, while for holes tau h approximately=4*10-6s. The quantum efficiency of the carrier generation process is 10-8 at about 400 K and is an exponential function of temperature with a thermal activation energy of 0.21 eV.