Stage structure in cesium doped pentacene Original Research Article

We have prepared the cesium doped pentacene film and have investigated the electrical properties, in order to investigate a new molecular conductive film based on pentacene. It was found that cesium is doped in the pentacene film and that electrical resistivity decreases drastically below 10 Ω cm. Moreover, in the doping process, we found the step-wise decrease of electrical resistivity. It is deduced from this result that the cesium doped pentacene forms stage structures. In addition, we have carried out the measurements of the X-ray diffraction pattern in the cesium doped pentacene film. It was found from these results that the cesium doped pentacene becomes a highly orientated intercalated conductive film. Furthermore, in the cesium doped pentacene we have observed the shift of (00l) diffraction peak to low diffraction angle. This result indicates that by doping of pentacene the c-axis lattice constant which is the length of the interval between the (001) planes becomes 1.59 nm in the stage-1 structure of the cesium doped pentacene.