Christophe Prat

P‐157: Electrical Modeling and Numerical Simulation of Doped Multilayer Organic Light‐Emitting Diodes (OLEDs)

This work aims at explaining and predicting the influence of dye doping and space charge effects on charge carrier transport at different operating temperatures. for that purpose, current-voltage J-V characteristics for typical electrically-doped multilayer OLEDs have been simulated. The results are in good agreement with experiment.

Electrical simulations of doped multilayer organic light-emitting diodes (OLEDs) under temperature stress for high current densities

— This work aims at explaining and predicting the influence of the thickness of organic materials, dye doping, and space-charge effects on charge-carrier transport at different operating temperatures for high current densities (50 ≤ J ≤ 7000 mA/cm2). For the purpose of determining these influences, current-voltage characteristics for typical electrically doped multilayer organic light-emitting diodes (OLEDs) have been simulated. The results of the simulations concur with experimental data.

58.2: Invited Paper: Novel High Efficiency Top Emission OLEDs for Display and Lighting Applications

We present results on low voltage and highly efficient OLED devices. The architecture based on doped transport layers is compatible with established manufacturing equipment, and shows long lifetime, good temperature stability, very low voltage drift, and very low heat dissipation. Main impacts are passive and active matrix displays with very low power consumption, use of a-Si backplanes, and realization of ITO free structures, e.g. for lighting applications.

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.