High air stability of threshold voltage on gate bias stress in pentacene TFTs with a hydroxyl-free and amorphous fluoropolymer as gate insulators

We investigated the air stabilities of threshold voltages(V-th) on gate bias stress in pentacene thin-film transistors (TFTs) with a hydroxyl-free and amorphous fluoropolymer as gate insulators. The 40-nm-thick thin films of spin-coated fluoropolymer had excellent electrical insulating properties, and the pentacene TFTs exhibited negligible current hysteresis, low leakage current, a field-effect mobility of 0.45 cm(2)/Vs and an on/off current ratio of 3 x 10(7) when it was operated at -20 V in ambient air. After a gate bias stress of 10(4) s, a small Vth shift below 1.1 V was obtained despite non-passivation of the pentacene layer. We have discussed that the excellent air stability of V,1, was attributed to the insulator surface without hydroxyl groups. (C) 2008 Elsevier B.V. All rights reserved.