New Low-Voltage Driving Compensating Pixel Circuit Based on High-Mobility Amorphous Indium-Zinc-Tin-Oxide Thin-Film Transistors for High-Resolution Portable Active-Matrix OLED Displays

Abstract

In recent years, active-matrix organic light-emitting diodes (AMOLEDs) has been the most popular display for portable application. To satisfy the requirement for the application of the portable display, the design of the compensating pixel circuit with the low-voltage driving and low-power consumption will be requested. In addition to the circuit with the design of the low-voltage driving, high-mobility thin-film transistors as driving device will be also necessary in order to supply larger driving current at low-voltage driving. Therefore, the study presents a new low-voltage driving AMOLED pixel circuit with high-mobility amorphous indium–zinc–tin–oxide (a-IZTO) thin-film transistors (TFTs) as driving device for portable displays with high resolution. The proposed pixel circuit can simultaneously compensate for the threshold voltage variation of driving TFT (ΔVTH_TFT), OLED degradation (ΔVTH_OLED), and the I-R drop of a power line (ΔVDD). By using AIM-Spice for simulation based on fabricated a-IZTO TFTs with mobility of 70 cm2V−1S−1 as driving devices, we discovered that the error rates of the driving current were all lower than 5.71% for all input data when ΔVTH_TFT = ±1 V, ΔVDD = 0.5 V, and ΔVTH_OLED = 0.5 V were all considered simultaneously. We revealed that the proposed 5T2C pixel circuit containing a high-mobility a-IZTO TFT as a driving device was suitable for high-resolution portable displays.

A Pixel Circuit for Compensating Electrical Characteristics Variation and OLED Degradation

“…As shown in Figure 2a, the circuit consists of one driving TFT (T2), four switching TFTs (T1, T3, T4, T5), and two capacitors (C1, C2). Therefore, lots of valuable voltage compensation pixel circuits have been reported [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In [17][18][19][20][21], the circuits can compensate the threshold voltage variation successfully.…”

“…Therefore, lots of valuable voltage compensation pixel circuits have been reported [17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In [17][18][19][20][21], the circuits can compensate the threshold voltage variation successfully. In [22][23][24][25], the circuits can compensate both threshold voltage and mobility variations successfully.…”

“…Therefore, lots of valuable voltage compensation pixel circuits have been reported [17][18][19][20][21][22][23][24][25][26][27][28][29][30].…”

“…In [17][18][19][20][21], the circuits can compensate the threshold voltage variation successfully. In [22][23][24][25], the circuits can compensate both threshold voltage and mobility variations successfully.…”

Effectiveness of Electrical and Optical Detection at Pixel Circuit on Thin-Film Transistors

“…Thus, the paper investigated whether the defect characteristics are based on open, short, and cross short defects on the thin-film transistor pixel circuit. On the other hand, the TFT resolution moves forward to the high-definition [ 7 , 8 , 9 ] as the market requests a wide view illumination coupled to the ultra-high definition. The pixel circuit in TFT is trending toward smaller and smaller dimensions.…”