Orientation-controlled growth of molecular organic thin films

The control of the structure and preferential orientation of molecular orga nic thin films might be achieved by the selection of suitable substrates th at, in general, have to be designed. Langmuir-Blodgett (LB) and self-assemb led monolayers (SAMs) films are good candidates as substrates due to the ch emical versatility of their surfaces. We illustrate an example of the selec tion of either of the two energetically most probable preferential orientat ions of polycrystalline neutral tetramethyltetraselenafulvalene (TMTSF) thi n films by the choice of different substrates. The films (thickness similar to1 mum), obtained by sublimation of TMTSF microcrystals in high vacuum (s imilar to 10(-6) mbar), are dominated by (0 -2 1)- and (100)-oriented micro crystals when using KBr (100) and methyl-terminated films, respectively.