New Fraction Time Annealing Method For Improving Organic Light Emitting Diode Current Stability of Hydorgenated Amorphous Silicon Thin-Film Transistor Based Active Matrix Organic Light Emitting Didode Backplane

Abstract

The distribution functions of the work performed on a twodimensional Ising model under the influence of an external magnetic field which is switched on and off are studied. These distributions are calculated by means of Monte Carlo simulations for temperatures below and above, as well as close to the critical temperature, T c , and for different rates of the switching processes. For this system the Jarzynski and the Crooks fluctuation theorems are verified. It is found that Crooks fluctuation theorem provides a faster method for evaluating free energy differences in this system with respect to the Jarzynski equality. As expected, for temperatures far from T c the convergence of the results is faster than for T T c , where a slower switching rate is needed. Results obtained from the theorems of Crooks and Jarzynski are compared with thermodynamic integration calculations and it is found that they agree very well within error bars.

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

“…Pixel circuits which can suppress the degradation of the a-Si:H driving TFT in an AMOLED pixel were also reported. 5,6 It is well known that the negative-gate-bias stress decreases V TH of a-Si:H TFTs. It may be attributed that the hole trapping into the SiN x gate insulator causes the negative V TH shift.…”

“…Negative-bias annealing involves applying a negative bias to the gate of an a-Si:H TFT, which improves the stability of the OLED current by suppressing the V TH shift. We have previously reported on fraction time annealing (FTA) 5 and polarity-balanced driving (PBD) 6 employing negative-bias annealing. However, the FTA scheme and the PBD scheme perform the negative-bias annealing by employing constant bias, i.e., the FTA and the PBD cannot apply a variable negative bias to the gate of a driving TFT according to the degradation level of each driving TFT.…”

“…FTA pixel circuit employing negative-bias annealing Figure 1(a) shows a three-TFT (3T) pixel employing fraction time annealing (FTA) that we have previously proposed. 5 The FTA scheme applies a negative bias to a gate of an a-Si:H TFT during a certain fraction time of each frame time. Figure 1(b) shows experimental results of the I OLED stability with various negative biases from -5 to -12.5 V when the negative duty cycle is set to 75% in each frame.…”

“…Figure 1(b) shows experimental results of the I OLED stability with various negative biases from -5 to -12.5 V when the negative duty cycle is set to 75% in each frame. 5 After V TH is degraded by a current driving stress of 8 µA, various negative bias are applied to reduce the induced V TH shift. After 12 hours of severe electrical bias and an elevated temperature of 60°C, I OLED of the proposed pixel (negative bias = -12.5 V, negative duty ratio = 75%) is decreased by only 6%, while that of a conventional one is decreased by 22%, which shows that the negative-bias annealing is very effective in improving the current stability of a-Si:H TFTs.…”

“…1(b) and our other experimental results. 5,9 Our proposed CDRNBA pixel circuit combines the V TH compensation and DRNBA in a frame, so that the V TH degradation can be minimized and the V TH shift of the DTR can be compensated even if the V TH shift is caused by the accumulation of the operation time to obtain a uniform and stable OLED current.…”