It is shown that the absorption properties in the visible region of polymer films based on mixtures of terthiophene and bithiophene may be tailored to suit the needs of optical devices such as solar cells, sensors and organic light emitting diodes. Using vapor phase polymerization (VPP) with iron(III) p-toluenesulfonate as the oxidant, the optimised films exhibit an extended absorption band in both directions when compared to films based only on bithiophene or terthiophene. Cyclic voltammetry reveals new bands not observed before in addition to redox bands attributed to both poly(terthiophene) and poly(bithiophene). The polymer chain length and conjugation length were estimated using Raman and UV-vis spectroscopy.