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In this paper, we propose a novel voltage-programmed pixel circuit with polysilicon thin–flim transistors (poly-Si TFTs) for active matrix organic light-emitting diode (AMOLED) displays, which consists of one programming transistor, one driving transistor, four switching transistors and two storage capacitors, respectively. Specifically, the proposed pixel circuit is able to not only efficiently compensate for the threshold variations of TFTs, but also largely suppresses the electrical degradations of the devices caused by the long-term electrical stress. Moreover, the mobility variation of the driving transistor can be compensated as well. The simulation has been performed by HSPICE, and results indicate that the average values of nonuniformities are, respectively, 7.3% as the threshold-voltage varies by $\pm 0.5$V and 2.1%, as the mobility of the driving transistor varies by $\pm 20$%, both of which are much lower than that of the conventional two-transistor and one-capacitor (2T1C) pixel. Furthermore, since the OLED is reverse-biased during the nonemission phases, the lifetime of OLED will be extended naturally. As a consequence, the proposed pixel circuit can substantially improve the display performance.

This paper proposes a stacked-capacitor pixel circuit for flexible AMOLED (Active Matrix-Organic Light Emitting Diode) displays based on the a-IGZO (Amorphous-Indium Gallium Zinc Oxide) TFT (Thin Film Transistor). A calibrated HSPICE level-61 a-IGZO TFT model is used for CAD simulations. The proposed design compensates for V${}_{\mathrm{\text{TH}}}$ shifts in the TFT by employing a stacked capacitor configuration for threshold voltage detection. The simulated results show a percentage error in the OLED current of less than 0.04% for a maximum tensile and compressive strain of 0.3%. The circuit can suppress the error in OLED current to 1.83% for a V${}_{\mathrm{\text{TH}}}$ shift in the range of 0 V to 2.1 V, from the nominal 0.7 V, with an input data voltage of 15 V. Therefore, the proposed pixel circuit topology proves to be a highly reliable pixel architecture which can be effectively used in AMOLED displays.