Self-assembly of poly(p-phenylene vinylene) using long chain counter-ion: a new process for fabrication of multilayer thin films heterostructures.

摘要

Layer-by-layer thin films of sulfoniun poly(p-phenylene vinylene) (PPV) precursor have been processed using the long chain dodecylbenzenesulfonate (DBS) anion. Here we adopted the alternative approach consisting of the controlled substitution of the chloride counterion of a water-soluble PPV precursor by DBS. The internal layer structure of these films is therefore likely to be different from conventional layer-by-layer films, since DBS ions are expected to be incorporated into the PPV precursor chain. The main advantage of this novel procedure is that thermal conversion through the elimination of DBS may be realized at considerably lower temperatures (80-100 deg C) in a few minutes, with enhanced optical properties. Using this new conversion procedure, the conjugation length can also be varied along the deposition direction by controlling the immersion time or DBS concentration in the film. This opens up a number of new possibilities to realize molecularly band-gap engineered structures such as asymmetric ladder type or "V-type" structures along the film.