Structure and Morphology of PDI8-CN2 for n-Type Thin-Film Transistors

A multiscale investigation of N,N?-bis(n-octyl)-x:y,dicyanoperylene-3,4:9,10-bis(dicarboximide), PDI8-CN2, shows the same molecular arrangement in the bulk and in thin films sublimated on SiO2/Si wafers. Non-conventional powder diffraction methods and theoretical calculations concur to provide a coherent picture of the crystalline structure. X-ray diffraction (XRD) and atomic force microscopy (AFM) analyses of films of different thickness deposited at different substrate temperatures indicate the existence of two temperature-dependent deposition regimes: a low-temperature (room temperature) regime and a high-temperature (80-120 °C) one, each characterized by different growth mechanisms. These mechanisms eventually result in different morphological and structural features of the films, which appear to be highly correlated with the trend of the electrical parameters that are measured in PDI8-CN2-based field-effect transistors.