Synthesis and Langmuir-Blodgett film of an alkyl substituted thiophene oligomer

alpha-Hexadecylterthiophene (C-16-3T) was synthesized and its chemical structure was confirmed by elemental analysis, IR and MS. Fabrication of Langmuir-Blodgett (LB) films of C-16-3T was described. The molecules can form stable monolayer at air-water interface with a collapse surface pressure up to 33 mN/m. The transfer ratios of 0.6-1.0 were obtained for an 18-layers LB film. The UV-visible absorption spectrum of C-16-3T as LB film is quite different in shape from the spectrum in solution, indicating that the intermolecular interaction is occurred in the LB system. Conductivity of the LB film along the parallel direction of the substrate at room temperature is 10(-3) S/cm and can be increased by one order of magnitude on doping with iodine.