Direct Visualization of the Nanoscale Morphology of Conducting Polythiophene Monolayers Studied by Electrostatic Force Microscopy

Understanding and control of the relation between the electronic transport properties and the morphology of conducting polymers is crucial for the further development and use of these materials because poor electronic properties of domain boundaries often limit the overall properties of the material. This is especially valid for field effect transistors, [1‐3] light emitting diodes, [4] and superconductivity in polymer compounds, [5‐7] where improved transport properties are essential for the further optimization of the organic materials as the electronically active layer in devices. The present paper provides the first direct images of the electronic domain structure in a conducting polymer thin film. The relation between structural and electronic properties of conducting polymers has previously been studied by various methods, including X-ray diffraction experiments [8‐12] and investigations of the temperature dependence of the conductivity [13‐16] as well as the electronic mobility. [17] The data have been evaluated by various models as for example Sheng’s fluctuation induced tunneling, [18,19] or a 1D resistor network model. [20] Although no specific model has been agreed upon, it is generally believed that transport in doped conducting polymers can be understood on the basis of a “metallic island” model, which is a composite model consisting of highly conducting crystalline regions surrounded by insulating amorphous regions. [21,22] However, a central unresolved issue is the