Enforced one-dimensional photoconductivity in core-cladding hexabenzocoronenes

Photoconductivity in contorted hexabenzocoronene liquid crystals is found to be exclusively one-dimensional. Spectroscopic measurements and density functional theory support the existence of two d-systems attributed to a low-energy radialene-core and higher energy out-of-plane alkoxyphenyl rings. Persistent photocurrents, measured as a function of field, channel length, and intensity, fit a stretched exponential characteristic of intracolumnar transport, restricted through the radialene-core by the alkoxyphenyl-cladding. Bimolecular recombination is enhanced with increasing carrier concentration by the system's one-dimensionality.