The Relationship between Structural and Electrical Characteristics in Perylenecarboxydiimide-Based Nanoarchitectures

The controlled assembly of the prototypical n-type organic semiconductor N, N'-1H, 1H-perfluorobutyl dicyanoperylenecarboxydiimide (PDIF-CN2) into ordered nanoarchitectures and the multiscale analysis of the correlation between their structural and their electrical properties is reported. By making use of the Langmuir-Blodgett (LB) technique, monolayers of PDIF-CN2 arranged in upright standing molecular packing on different substrates are formed. Postdeposition thermal treatment makes it possible to trigger a reorganization into layered ultrathin crystalline nanostructures, exhibiting structural and photophysical properties similar to those of microscopic crystals obtained by solvent-induced precipitation. The controlled engineering of these molecular architectures on surfaces enables us to identify both a dependence of the monolayer resistance on the molecular tilt angle in vertical junctions and a pronounced charge-transport anisotropy with enhanced transport along the pi-pi stacking direction of the PDI core. While a charge carrier mobility for electrons as high as 10(-2) cm(2) V-1 s(-1) is determined in monolayer field-effect transistors for the in-plane direction, being the highest yet reported value for a n-type LB monolayer, the out-of-plane mobility measured by conductive atomic force microscopy in multilayered structures is found to be one order of magnitude lower.