Conducting polymers as substrates for surface-mounted molecular devices

Thin films of poly(3,4-diethoxythiophene), PEDOT, were prepared by vacuum sublimation/polymerization of 2,5-dibromo-3,4-ethylenedioxythiophene onto freshly cleaved mica. AFM studies show that the films are exceptionally smooth and contain both highly crystalline and amorphous regions. Exposure of the film to polar solvents for one hour causes an increase in the surface roughness, while exposure to non-polar solvents or thermal annealing decreases surface roughness. Ary thiols linked to diazo dye labels can be covalently bound to the films by simple exposure in dilute methylene chloride solutions. This provides a convenient way to functionalize PEDOT surfaces with molecular devices.