3-Methylcyclohexanone Processed n-Channel Organic Thin-Film Transistors Based on A Conjugated Polymer Synthesized by Direct Arylation Polycondensation

The solubility of a direct arylation polycondensation (DArP) synthesized conjugated polymer, i.e. , poly(3,6-bis(furan-2-yl)-2,5-bis(4-tetradecyloctadecyl)-pyrrolo[3,4-c]pyrrole-1,4(2 H ,5 H )-dione-alt-1,2-bis(3,4-difluorothien-2-yl)ethene) (PFuDPP-4FTVT), in various organic solvents was studied. The polymer is soluble in 3-methylcyclohexanone (3-MC), a green solvent from peppermint oil, besides other solvents such as anisole, cyclopentyl methyl ether (CPME) and o -dichlorobenzene ( o -DCB), etc . Based on the Hansen solubility parameters (HSP) analysis, 3-MC is identified as a “marginal solvent” of PFuDPP-4FTVT. The morphology of the spin-coated films with 3-MC as the solvent strongly correlated with the solution preparation conditions. With a 3-MC solution aged for 3 h at 70 °C, n-channel organic thin-film transistors (OTFTs) with electron mobility ( μ e ) above 1 cm 2 ·V −1 ·s −1 and current on/off ratio ( I on / I off ) higher than 10 5 were fabricated by spin-coating. This is the first report on high mobility conjugated polymers for OTFTs processible with naturally occurred green solvent.