14:15 〜 14:30
▲ [21p-B32-6] Phytol-derived alkyl side chains for π-conjugated semiconducting polymers
キーワード：semiconducting polymer, alkyl side chain, molecular orientation
The solution-processability of π-conjugated semiconducting polymers is regarded as an important characteristic for the potential application in large-area printed flexible electron devices that distinguishes them from inorganic semiconductors. In fact, the solubility of semiconducting polymers largely relies on alkyl side chains and side chains meanwhile have a significant impact on interchain packing, molecular orientation, and polymer morphology in films, which are features that are known to affect device performance.
In this study, we propose the use of phytol-derived alkyl side chains in π-conjugated polymers. Diketopyrrolopyrrole (DPP)-based semiconducting polymers were synthesized with the side chains of 3,7,11,15-tetramethylhexadec-2-en-1-yl (TMHDe) and 3,7,11,15-tetramethylhexadecyl (TMHD) that are derived from phytol. The properties of these polymers were compared to those of DPP-2-octyldodecyl (DPP-OD), a polymer comprising a conventional branched alkyl side-chain having the same number of carbon atoms as TMHDe and TMHD. In diluted solutions, DPP-TMHDe and DPP-TMHD showed good solubility in organic solvents and had longer effective conjugation lengths than DPP-OD. In thin films, the introduction of the TMHDe and TMHD side chains into the DPP-based polymers leads to the higher crystallinity with highly ordered edge-on oriented polymer backbones and shorter π-π stacking distance than the introduction of the branched OD chain. These differences result in 3–5-fold higher hole mobility in organic field effect transistors (OFETs). The device performance of OFETs based on DPP-TMHD was characterized by a particularly high thermal stability, up to a temperature of 250 °C, resulting from the robust packing structure of the polymer. The use of these phytol-based solubilizing groups in extended π-conjugated molecules can be a useful design strategy to strike a good balance between molecule solubility and relevant thin-film crystallinity.
In this study, we propose the use of phytol-derived alkyl side chains in π-conjugated polymers. Diketopyrrolopyrrole (DPP)-based semiconducting polymers were synthesized with the side chains of 3,7,11,15-tetramethylhexadec-2-en-1-yl (TMHDe) and 3,7,11,15-tetramethylhexadecyl (TMHD) that are derived from phytol. The properties of these polymers were compared to those of DPP-2-octyldodecyl (DPP-OD), a polymer comprising a conventional branched alkyl side-chain having the same number of carbon atoms as TMHDe and TMHD. In diluted solutions, DPP-TMHDe and DPP-TMHD showed good solubility in organic solvents and had longer effective conjugation lengths than DPP-OD. In thin films, the introduction of the TMHDe and TMHD side chains into the DPP-based polymers leads to the higher crystallinity with highly ordered edge-on oriented polymer backbones and shorter π-π stacking distance than the introduction of the branched OD chain. These differences result in 3–5-fold higher hole mobility in organic field effect transistors (OFETs). The device performance of OFETs based on DPP-TMHD was characterized by a particularly high thermal stability, up to a temperature of 250 °C, resulting from the robust packing structure of the polymer. The use of these phytol-based solubilizing groups in extended π-conjugated molecules can be a useful design strategy to strike a good balance between molecule solubility and relevant thin-film crystallinity.