High permittivity dielectrics for poly(3-alkylthiophene) field-effect transistor devices

Abstract

In an attempt to disentangle the effects of permittivity and surface energy of the gate insulator (expressed by its dielectric constant k and water contact angle, respectively) on the performance of organic field-effect transistors (FETs), we fabricated top- and bottom-gate FET architectures with poly(3 -alkylthiophenes) (P3ATs) of different side-chain lengths, using a range of gate dielectrics. We find that this class of semiconductor, including the short butyl-(C 4–) substituted derivative, is significantly less susceptible to the often detrimental effects that high- k dielectrics can have on the performance of many organic FETs. For bottom gate devices we identify the surface energy of the gate dielectric to predominantly dictate the device mobility.