Mesomorphic phthalocyanines, tetraazaporphyrins, porphyrins and triphenylenes as charge-transporting materials

The columnar mesomorphism of triphenylene-, phthalocyanine-, tetraazaporphy rin- and porphyrin-based compounds is briefly reviewed and the potential us e of this particular supramolecular structure for charge-conducting devices is discussed. Suitably substituted triphenylenes exhibit ideal material pr operties for photoconducting devices, and well-aligned layers have been sho wn to give a very high charge carrier mobility of 0.1 x 10(-4) m(2) V-1 s(- 1) (time-of-flight measurements). From a molecular point of view, porphyrin systems should be superior to triphenylenes, but the properties of their m esophases do not support the advantageous homeotropic alignment of the colu mnar stacks. However, pulse radiolysis time-resolved microwave conductivity measurements revealed the highest charge carrier mobility value of 0.28 x 10(-4) m(2) V-1 s(-1) for mesomorphic phthalocyanines. Copyright (C) 2000 J ohn Wiley & Sons, Ltd.