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

摘要

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 fluoro-polymer 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 × 10~7 when it was operated at -20 V in ambient air. After a gate bias stress of 10~4 s, a small V_(th) shift below 1.1 V was obtained despite non-passivation of the pentacene layer. We have discussed that the excellent air stability of V_(th) was attributed to the insulator surface without hydroxyl groups.