Enhanced carrier mobility and electrical stability of n-channel polymer thin film transistors by use of low-k dielectric buffer layer

Insertion of a low- k polymer dielectric layer between the SiO 2 gate dielectric and poly(benzobisimidazobenzophenanthroline) (BBL) semiconductor of n-channel transistors is found to increase the field-effect mobility of electrons from 3.6×10 −4 cm 2 /Vs to as high as 0.028 cm 2 /Vs. The enhanced carrier mobility was accompanied by improved multicycling stability and durability in ambient air. Studies of a series of eight polymer dielectrics showed that the electron mobility increased exponentially with decreasing dielectric constant, which can be explained to result from the reduced energetic expense of charge-carrier/dipole interaction.