Enhanced charge conduction in discotic liquid crystals

At relatively low electric fields the conduction of thin films (2-6 mum) of the discotic liquid crystal (HAT6-PTP9) sandwiched between ITO electrodes and homeotropically aligned is low and is consistent with space-charge limited behaviour. However when annealed at high temperatures and electric fields the films undergo a transition and the electrical conductivity increases by up to 5-6 orders of magnitude. Studies show that this increase in the conductivity is not due to filament growth or to bulk molecular breakdown but rather to some chemical or physical change at the electrode surface.