  Indacenodithiophene (IDT) based materials are emerging high performance
conjugated polymers for use in efficient organic photovoltaics and transistors.
However, their preparation generally suffers from long reaction sequences and
is often accomplished using disadvantageous Stille couplings. Herein, we
present detailed synthesis pathways to IDT homopolymers using C-H activation
for all C-C coupling steps. Polyketones are first prepared by direct arylation
polycondensation (DAP) in quantitative yield and further cyclized polymer
analogously. This protocol is suitable for obtaining structurally well-defined
IDT homopolymers, provided that the conditions for cyclization are chosen
appropriately and that side reactions are suppressed. Moreover, this polymer
analogous pathway gives rise to asymmetric side chain patterns, which allows to
fine tune physical properties. Alternatively, IDT homopolymers can be obtained
via oxidative direct arylation polycondensation of IDT monomers (oxDAP),
leading to IDT homopolymers with similar properties but at reduced yield.
Detailed characterization by NMR, IR, UV-vis and PL spectroscopy, and thermal
properties, is used to guide synthesis and to explain varying field-effect
transistor hole mobilities in the range of 10-6- 10-3 cm2/Vs.
