Extended conjugation in poly(triarylamine)s: synthesis, structure and impact on field-effect mobility

Polytriarylamines with extended fused backbones are accessible by the coupling of anilines with dibromoarenes based on substituted indenofluorenes, diindenofluorenes, carbazoles and indolocarbazoles. The optical and electrochemical properties of these polymers show an increase in the HOMO energy levels and the onset of absorption on extending the length of the fused ring segment. The polymer derived from the indenofluorene unit shows the highest reported performance for a polytriarylamine in an OFET and this observation can be rationalized by DFT calculations of model oligomers that show higher calculated reorganization energies for the more extended diindenofluorene units.