Epitaxial growth of quaterthiophene thin films by organic molecular beam deposition

Organic molecular beam deposition (OMBD) in ultra-high vacuum is a valuable technique to carefully control the solid-state structure and properties of molecular thin films. Quaterthiophene (4T) and alpha,omega -dihexyl-quaterthiophene (DH4T) thin alms deposited by OMBD on potassium acid phthalate are investigated by atomic force microscopy (AFM). Direct evidence of epitaxial growth of the thin films is obtained by molecular resolution AFM images. The comparison between 4T and DH4T films reveals the role of chemical substituent groups in modifying the film properties