a-Si∶H-TFT阈值电压漂移机理及其在驱动OLED显示中的补偿设计

Mechanisms for a-Si∶H-TFT Threshold Voltage Shift and its Compensative Design in Driving OLED Displays

分析了a-Si∶H-TFT阈值电压漂移的机理,即分析了栅偏应力下电荷注入到SiNx∶H栅绝缘层和a-Si∶H中亚稳态的产生对TFT阈值电压漂移的影响。根据非晶硅中亚稳态产生的特点,并针对驱动OLED的两管a-Si∶H-TFT像素电路,提出了一种通过对数据信号时序的重新设计来补偿阈值电压漂移的方法,即在数据信号间加插一个与数据信号极性相反的补偿信号。通过这种正负交替的信号,使驱动管TFT中由亚稳态造成的阈值电压漂移始终保持在一个动态平衡的过程,来实现驱动OLED电流稳定的目的。

The mechanisms for a-Si： H-TFT threshold voltage shift were analyzed. That is, the influence of charges injecting into SiNs ：H gate insulator and the creation of meta-stable states in a-Si： H to a-Si： H-TFT threshold voltage shift under gate bias stress were analyzed. According to the characteristics of the meta-stable states in a-Si： H, and two a-Si： H TFT pixel circuit driving OLED display, a new data signal timing in order to compensate the threshold voltage shift was designed. That is, one compensative signal, whose polarity was inverse to data signal, was inserted between data signals. By this kind of signals with alternative polarity, positive and negative respectively, the threshold voltage shift for driving TFT, resulting from the meta-stable states in a-Si： H, would be kept in a dynamic equilibrium process, thus to realize OLED lighting stability.