Ambipolar carrier transport properties in a built-in donor-acceptor discogen

Carrier transport in the hexagonal columnar mesophase of a discogen with a built-in dipole moment in the core-hexaalkoxydibenzo[a,c]phenazine (HDBP-3) was investigated. The temperature and field dependences of bipolar carrier mobilities up to the order of 10(-3)-cm(2)V(-1)s(-1) in the homeotropically aligned HDBP-3 have been revealed by time-of-flight (TOF) measurement. One-dimensional hopping model was used to discuss the effect of built-in donor-acceptor molecular dipole in the core. The calculation of charge transfer integral also supported the results of mobility measurement. The donor-acceptor molecular dipole in the discogen not only stabilized the mesophase but also contributed to the nondispersive ambipolar nature and substantially enhanced the electron transport in HDBP-3. (C) 2013 Elsevier B.V. All rights reserved.