An averaging pixel structure using microcrystalline‐silicon films prepared at high temperature for AMOLED displays

Abstract— A new voltage‐addressed pixel using a multiple drive distribution has been developed to improve, in a simple way, the brightness uniformity of active‐matrix organic light‐emitting‐diode (AMOLED) displays. Moreover, circuits were realized using microcrystalline‐silicon (μc‐Si) films prepared at 600°C using a standard low‐pressure CVD system. The developed p‐channel TFTs exhibit a field‐effect mobility close to 6 cm²/V‐sec. The experimental results show that the proposed spatial distribution of driving TFTs improves the uniformity of current levels, in contrast to the conventional two‐TFT pixel structure. Backplane performances have been compared using circuits based on μc‐Si and furnace‐annealed polysilicon materials. Finally, this technology has been used to make an AMOLED demonstration unit using a top‐emission OLED structure. Thus, by combining both an μc‐Si active‐layer and a current‐averaging driver, an unsophisticated solution is provided to solve the inter‐pixel non‐uniformity issue.