Reducing OLED Degradation Using Self-Compensated Circuit for AMOLED Displays

In this letter, the electric characteristics of the fabricated organic light-emitting diode (OLED) devices are analyzed after a bias stress. Experimental results demonstrate that when a constant voltage is applied to the OLED device, the OLED threshold voltage gradually increases, resulting in the driving current to decay. Therefore, a novel voltage driving scheme for active-matrix OLEDs using low-temperature polysilicon thin-film transistors (poly-Si TFTs) is proposed. This circuit uses three TFTs to increase the aperture ratio of panels and the driving current of the OLED device to ameliorate the luminance drop that is caused by OLED degradation. Simulation results indicate that the proposed pixel circuit has high immunity to $V_{\rm TH}$ variations of the poly-Si TFTs and provides an extra compensation current against OLED degradation.