Stage structure and electrical properties of rubidium-doped pentacene

We have investigated the structural and electrical properties on the molecular conductor based on pentacene doped with rubidium. It was found from the X-ray diffraction measurement that the rubidium-doped pentacene becomes a highly oriented film with a stage-1 structure, as seen in graphite intercalated compounds. It was also found from this result that the length between pentacene molecular layers increases from 1.51 mn of pure pentacene to 1.62 nm. Moreover, the result of the electrical conductivity measurement shows that by doping of rubidium electrical conductivity at room temperature increases above 108 times larger than that of pure pentacene. We have also found that the electrical conductivity along the a-b plane (parallel to the molecular layers) is 102 times larger than that along the c-axis which is perpendicular to the molecular layers. These results indicate that pentacene doped with rubidium becomes a molecular conductor and displays the quasi-two-dimensional conductivity. (C) 2003 Elsevier B.V. All rights reserved.