Summary:
In this work a synthetic process is described, to produce semiconducting
polymers (mainly for use in organic photovoltaics), the active layers of which
may self-organize in the nanoscale and form a morphology of “optimal
heterojunction” type with a simultaneously tuneable band gap. In this way, the
main problem of low conversion efficiency observed in the common “bulk
heterojunction” photovoltaics will be hopefully overcome. For the achievement
of an “optimal heterojunction”, a bottom-up supramolecular self-organization is
implemented, in order to receive new well-defined structures of the respective
active semiconductive layers.
Block copolymers of poly(3-hexylthiophene), P3HT, and polystyrene, PS, serving
as donor/insulator layer, are synthesized via controlled anionic
polymerization, Kumada catalyst-transfer polycondensation and click chemistry
techniques. The final materials are expected to present the ability to
hierarchically self-assemble creating hexagonally-packed cylinders of P3HT in
the polystyrene matrix, alternating lamellae morphologies, or cylinders of
polystyrene in the P3HT matrix. The synthetic effort leads to the overall
control of the morphology and composition of the donor/insulator layer.
All novel monomers and polymers synthesized were extensively characterized with
regards to their chemical structure, as well as optical and morphological
properties via Size Exclusion Chromatography, Nuclear Magnetic Resonance,
Infrared Spectroscopy, Ultraviolet–Visible Spectroscopy, Thermogravimetric
Analysis and Differential Scanning Calorimetry techniques.
Keywords:
Anionic polymerization, Kumada catalyst-transfer polycondensation, Polystyrene, Conjugated polymers of 3-hexylthiophene, Photovoltaic cells
