A novel 3-TFT voltage driving method of compensating VTH shift for a-Si:H TFT and OLED degradation for AMOLED

This work demonstrates the feasibility of a novel pixel circuit by using three a-Si:H TFTs. The proposed circuit can stabilize the OLED current and provide an additional driving current to ameliorate the brightness degradation of the AMOLED. Measurement results indicate that the current degradation of the proposed circuit, caused by VTH variations, is less than 5% over more than 50,000 s at 60 °C, whereas that of a conventional 2T1C pixel circuit is larger than 34%. Furthermore, to ameliorate the decrease in luminance owing to the OLED degradation, the OLED current can be increased by 10% by analyzing the current degradation and modulating the detected voltage appropriately.

► The proposed pixel circuit was fabricated by using a standard a-Si:H processes.
► After 48 h stress, this study can stabilize OLED current against VTH shift throughout the whole data voltage.
► A lifetime test for 50,000 s at 60 °C, current decay is less than 5%, while that of traditional circuit is 34%.
► Reducing VDET can increase OLED current by 10% to ameliorate luminance degradation.
► Luminance of proposed 3T1C pixel circuit with fabricated OLED can keep as the same as the initial value.