Preparation of Polythiophene Films by UV Laser-Assisted Deposition of Thiophene Derivatives.

Polythiophene thin films are prepared from several thiophene derivatives, such as 2, 5-dichlorothiophene(DCT), 2, 5-dibromothiophene(DBT) and 2, 5-diiodothiophene(DIT) by UV laser-assisted deposition (UV-LAD) with 193 (ArF), 248 (KrF) and 308nm (XeCl) beams. Each film prepared by UV-LAD possesses highly oriented fibrous structure called laser induced periodic structure (LIPS). Electric conductivities of some films have increased from less than 10-7S cm-1 up to 10-3S cm-1 by doping with iodine after UV-LAD. FT-IR, ESCA and UV-vis. spectra show that, although sulfur atoms are eliminated to some extent, polymerization basically occurs at 2(α)-5(α′) positions of the thiophene derivatives by elimination of halogen atoms. For the film prepared by UV-LAD of DIT at 308nm, the average conjugation length is estimated to be corresponding to that of thiophene oligomers consisting of 4±1 thiophene units.