Effect of annealing on the properties of thin films of free base phthalocyanine and perylene-3,4,9,10-tetracarboxylic dianhydride deposited by organic molecular beam deposition

Organic molecular beam deposition (OMBD) has been used to deposit thin films of free base phthalocyanine (H2Pc) and perylene-3,4,9, 10-tetracarboxylic dianhydride (PTCDA). The structural, optical and morphological properties of the films have been measured as a function of annealing temperature using x-ray diffraction (XRD), electronic absorption spectroscopy and atomic force microscopy (AFM). A phase transition, (alpha-beta), is observed for H2Pc films which is accompanied by changes in the bulk film properties and surface morphology. In the case of PTCDA increasing temperature does not affect the structural and optical properties of the film, but different surface morphologies are observed.