High mobility organic field-effect transistors based on defect-free regioregular poly(3-hexylthiophene-2,5-diyl)

• We demonstrate high performance organic field effect transistors based on defect free 100% regioregular P3HT.
• We used cross-linked poly(vinyl alcohol) as gate insulator.
• The field-effect mobility achieves values higher than 1 cm2/V s.

We report on organic field-effect transistors (OFETs) prepared using defect free (100% regioregular) poly(3-hexylthiophene-2,5-diyl) (DF-P3HT) as semiconductor and cross-linked poly(vinyl alcohol) (cr-PVA) as gate insulator. High field-effect mobility (μFET) of 1.2 cm2 V−1 s−1 is obtained and attributed to the absence of regioregularity defects. These transistors have transconductance of 0.35 μS and the DF-P3HT film shows larger crystallites (∼80 Å) than a highly regioregular (>98%) material (∼32 Å). Devices with increased μFET (2.8 cm2 V−1 s−1) could be obtained at the expense of the On-Off current ratio, which was reduced by one order of magnitude, when poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) treatment was applied to the dielectric surface. Our results suggest that the interaction of charged sites at the dielectric surface with regioregularity defects of the P3HT is an important factor degrading μFET even at very low concentration of regioregularity defects.

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