A Study of Thin Film Encapsulation on Improving Electrical Characteristics and Reliability for Flexible OLEDs

In this work, we investigated the effect of thin film encapsulation on Vth shift in a-IGZ0 TFTs. The result shows that decreasing the NH3 flow rate of deposited SiON films, the trend of Vth shift under the operation mode can vary from negative to positive direction, which can be attributed to lower amount of hydrogen diffused from SiON to the a-IGZO TFTs. Beside, we designed the TFE with stable inorganic-organic-inorganic stack structure, of which the CVD1 deposited with low NH3 flow rate and the CVD2 with high barrier property, and a 16.9-inch high performance flexible OLED panel with controlled Vth shift and RA lifetime over 475 h was achieved at the condition of 85 °C and 85% RH. This study demonstrates the influence of TFE on a-IGZO TFTs, and offers an optimized TFE structure which promises both electrical characteristics and reliability for flexible OLEDs.