All-organic thin-film transistors made of poly(3-butylthiophene) semiconducting and various polymeric insulating layers

We have fabricated fully patterned all-organic thin-film transistors with a variety of organic polymer insulators. Poly(3-butylthiophene) deposited by spin coating was used as the active organic layer. We have built top-gate structures with gates printed on top of the gate dielectric layer. The field enhanced current is weak with poly(4-vinyl phenol), but much stronger with polyvinyl alcohol and cyanoethylpullulan. Carrier mobilities as large as 0.04 cm2/V s were measured in the case of cyanoethylpullulan. A strong correlation is found between the solvents used for the dielectrics, dielectric constant of the insulator, and the field-effect mobility.