Anisotropic ambipolar carrier transport and high bipolar mobilities up to 0.1cm2V−1s−1 in aligned liquid-crystal glass films of oligofluorene

Abstract

By taking advantage of the rich morphological characteristics of oligofluorenes and the mesophase-mediated molecular assembly/alignment, we studied carrier-transport properties of solid-state oligofluorenes in different morphologies and orientations. Compared to the amorphous phase, the uniaxially aligned liquid-crystal glass of oligofluorenes could give up to 100-fold enhancement in bipolar carrier-transport mobilities, bringing both hole and electron mobilities to nearly 0.1cm2∕Vs. Furthermore, significant anisotropic bipolar transport, i.e., preferential bipolar carrier transport along the oligomer chain direction is observed.