Correlation of mobility and molecular packing in organic transistors based on cycloalkyl naphthalene diimides

A series of cycloalkyl-substituted naphthalene tetracarboxylic diimides (Cyn-NTCDIs, n= 3-8) are prepared and the transistor properties and molecular packings are systematically investigated. Cy5-Cy8-NTCDIs have similar brickwork structures, where two molecules are located on the top of a molecule with large displacement along the molecular shortaxis. The intermolecular overlap is maximized when the small slipping along the molecular longaxis makes the molecules nearly perpendicular to the substrate. Consequently, the mobility decreases exactly in the same order as the interlayer d-spacings.