First Electronic Conduction with High Hole Mobility in Smectic a Phase of a Calamitic Liquld Crystal

Abstract Liquid crystalline photoconductor 2-(4′-heptyloxypheny1)-6-dodecylthiobenzothiazole was designed and its carrier transport characteristics was measured with Time-of-Flight (TOF) technique. In crystal state, only transient current decay originating from a capturing process of photo-generated carriers by deep traps formed at grain boundaries was observed. In smectic A (SmA) phase, non-dispersive transient photocurrent based on fast hole transport was observed, in which hole mobility was 5×10−3 cm/Vs, independent of electric field. In isotropic phase, ambipolar transport proceeded and the mobilities of both positive charge and negative charge carriers were on the order of 10−5 cm2/Vs.