Arc'Hanmael Gaillard

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

— 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.

A New Active Pixel Design using μc-Si TFT Technology to Improve Brightness Uniformity of Organic Displays

In this paper, we propose and fabricate a new active pixel circuit design integrated on active-matrix organic light-emitting diode (AMOLED) display. Moreover, we have developed a thin film transistor (TFT) based on microcrystalline silicon (μc-Si) active layer for a more efficient process and a better uniformity of driving transistor characteristics. The experimental results show that the emission current uniformity is improved in contrast to the conventional 2-TFT pixel circuit. Thus the proposed averaging driver successfully improves the inter-pixel uniformity.