A new a‐Si:H TFT pixel circuit employing data‐reflected negative‐bias annealing for a stable and uniform AMOLED

— A new a-Si:H pixel circuit to reduce the VTH degradation of driving a-Si:H thin-film transistors (TFTs) by data-reflected negative-bias annealing (DRNBA) is presented. The new pixel circuit compensates VTH variation induced by non-uniform degradation of each a-Si:H pixel due to various electrical stress. The proposed pixel circuit was verified by SPICE simulations. Although the VTH of the driving a-Si:H TFT varies from 2.5 to 3.0 and 3.5 V, the organic light-emitting diode (OLED) current changes by only 1.5 and 2.8% in the emission period, respectively. During the negative-bias annealing period, the negative VGS is applied to the driving TFT by using its own data signal. It is expected that the VTH shift of the driving TFT can be effectively reduced and the VTH shift can be compensated for in our new pixel circuit, which can contribute to a stable and uniform image from an a-Si:H TFT active-matrix OLED.