Highly reliable a-IGZO TFTs on a plastic substrate for flexible AMOLED displays

We have successfully reduced threshold voltage shifts of amorphous In–Ga–Zn–O thin-film transistors (a-IGZO TFTs) on transparent polyimide films against bias-temperature stress below 100 mV, which is equivalent to those on glass substrates. This high reliability was achieved by dense IGZO thin films and annealing temperature below 300 °C. We have reduced bulk defects of IGZO thin films and interface defects between gate insulator and IGZO thin film by optimizing deposition conditions of IGZO thin films and annealing conditions. Furthermore, a 3.0-in. flexible active-matrix organic light-emitting diode was demonstrated with the highly reliable a-IGZO TFT backplane on polyimide film. The polyimide film coating process is compatible with mass-production lines. We believe that flexible organic light-emitting diode displays can be mass produced using a-IGZO TFT backplane on polyimide films.