64.3: Amorphous Silicon Thin-Film Transistor Backplane on Stainless Steel Foil Substrates for AMOLEDs

We developed a hydrogenated amorphous silicon (a‐Si:H) thin‐film transistor (TFT) process on stainless steel (SS) foil substrates for high uniformity of TFT characteristics. The a‐Si:H TFTs with channel length of 5μm showed a mobility of ∼0.3cm2/Vs and a threshold voltage of ∼4.5 V, which are similar to those of TFTs on glass substrates. We designed a pixel circuit with two a‐Si:H TFTs and fabricated a 70ppi active‐matrix organic light‐emitting display (AMOLED) backplane on 75μm thick SS foil substrates. The pixel circuit can provide OLED current of up to 9.2μA at VDD=20V, Vscan=20V, and Vdata=15V. This current level can produce a luminance of greater than 500cd/m2 by an AMOLED using a white OLED with a luminous efficiency greater than“12cd/A and RGBW color filters.