Structural characterization of tetrahexyl sexithiophene ordered films grown by organic molecular beam deposition

The deposition of thin films of 3,3 ",4''',3'''''-tetrahexyl-2,2':5',2 ":5 ",2''':5''',2''''':5''''',2'''''-sexithiophene (4H6T) has been performed in ultra-high vacuum conditions by using organic molecular beam deposition (OMBD). Once temperature and pressure are optimized, the substrate choice is the key factor in determining the properties of the deposited films. From the structural analysis of samples deposited on different inorganic and organic substrates as well as from the comparison with crystalline polymorphs of 4H6T, useful information for the control of both structural order and molecular orientation in the films are inferred. The results of structural investigations by X-ray diffraction, compared with optical analyses (electronic absorption and photoluminescence), are indicative of either intermolecular or substrate-4H6T interactions.