Synthesis of highly transparent conductive films with strong absorption in near-infrared region based on tetrathiafulvalene-tethered pendant-type polymers

The conductive materials which have both of high transparency in the visible region and large light-absorbing ability in the near infrared (NIR) are promised to be feasible not only for improving the properties of current optoelectronic devices but also for developing advanced materials. To realize these optical and electric properties using the all-organic materials, we constructed the conductive materials based on the tetrathiafulvalene (TTF)-tethered polymers. We designed and synthesized the TTF-tethered polymers to gather all TTF molecules into the nanofibers and to control the dispersion of the TTF nanofibers in the films. We obtained the soluble polymers with various amounts of TTF units in conventional organic solvents. In addition, it was confirmed that the nanofibers containing the mixed-valence state of TTF were formed in the polymer matrices, leading to the strong light-absorption in the NIR region. Furthermore, the resulting thick films showed high transparency in the visible region and similar conductivity as a semiconductor.