ABSTRACT
The incorporation of heteroatoms in the chemical structure of organic molecules has been identified as analogous to the doping process adopted in silicon semiconductors to influence the nature of charge carriers. This strategy has been an eye-opener for material chemists in synthesizing new materials for optoelectronic applications. Phenanthro[9,10-a]phenazine-based mesogens have been synthesized via a cyclo-condensation pathway involving triphenylene-based diketone and o-phenyl diamines. The incorporation of phenazine moiety as discussed in this paper, alters the symmetric nature of the triphenylene. The phenanthro[9,10-a]phenazine-based mesogens exhibit hole mobility in the order of 10-4â cm2/Vs as measured by the space-charge limited current (SCLC) technique. The current density in the SCLC device increases with increasing temperature which indicates that the charge transport is associated with the thermally activated hopping process. This report attempts to elucidate the self-organization of asymmetric phenanthro[9,10-a] phenazine in the supramolecular liquid crystalline state and their potential for the fabrication of high-temperature optoelectronic devices. However, the low charge carrier mobility can be one of the challenges for device performance.
ABSTRACT
A new series of highly soluble perylene anti-bis(4,5-dialkoxybenzimidazole)s bearing branched flexible chains stabilizing room temperature columnar hexagonal phase and with balanced ambipolar charge carrier mobility is reported for the first time. Only the anti isomer was successfully separated and characterized. These compounds have a high extinction coefficient, small optical band gap and wide absorption range, thus making them a promising class of ambipolar organic semiconductors capable of self-organizing.