Nucleation and shape of 2D islands of DPh-DNTT thin-films prepared by vacuum evaporation

The growth mechanism of 2,9-diphenyl-dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DPh-DNTT) thin-films prepared by vacuum evaporation was investigated from a view point of the morphological crystallinity. In addition to atomic force microscopy, which is commonly used for imaging the morphology of surfaces, optical microscopy was positively used for the same purpose. The method allows quick and easy evaluation of the thin-film. In fact, an isolated, round, monolayer 2D island on the SiO
₂
substrate in initial stage and fractal-shape 2D islands on top surface of thin-film were observed. The nucleation density which depends on substrate temperature and surface treatment was investigated to clarified the growth mechanism.