Highly stable amorphous-silicon thin-film transistors on clear plastic

Hydrogenated amorphous-silicon (a-Si:H) thin-film transistors (TFTs) have been fabricated on clear plastic with highly stable threshold voltages. When operated at a gate field of 2.5×105V∕cm, the threshold voltage shift extrapolated to only ∼1.2V after ten years. This stability is achieved by a high deposition temperature for the gate silicon nitride insulator which reduces charge trapping and high hydrogen dilution during a-Si:H growth to reduce defect creation in a-Si:H. This gate field of 2.5×105V∕cm is sufficient to drive phosphorescent organic light emitting diodes (OLEDs) at a brightness of 1000Cd∕m2. The half-life of the TFT current is over ten years, slightly longer than the luminescence half-life of high quality green OLEDs.