The X-ray diffraction pattern of vacuum sublimed thin films of lead phthalo
cyanine on glass substrates shows a partially monoclinic structure. The DC
conduction is extrinsic since the activation energy is much smaller than th
e energy bandgap. AC conductivity sigma(ac) follows a power law dependence
on frequency (f) for T less than or equal to 230K and 20Hz less than or equ
al to f less than or equal to 320kHz range, and this behaviour is believed
to be due to correlated hopping of charge carriers over a reduced interclus
ter potential barrier of 0.49eV and a minimum distance of 6.7nm. Above 230K
, the dielectric polarisation occurs due to structural inhomogeneities with
a distribution of relaxation times. The conduction becomes independent of
temperature at 1 MHz.