Smectic mesophases in the calamitic liquid crystalline materials such as 2-phenylnaphthalene derivatives exhibit fast ambipolar carrier transport, whose mobility is up to 10(-2) cm(2)/Vs. For these mesophases, we have investigated the effect of defects in the bulk and at the domain boundary on these carrier transport by measuring transient photocurrents in thick cells up to 120 mum in thickness and in the cells of different domain sizes of 10 similar to 100s mum. It was found that non-dispersive carrier transports was observed for all the cells and the carrier transport was affected neither by cell thickness nor by domain sizes. Thus, it was concluded that there are few deep defects in the bulk and that the domain boundary is electrically inactive in these mesophases, demonstrating their high potential for practical application to large-area electronic devices.