Work

a-IGZO TFT Pixel Circuit With Double Gate Structure for Compensation of V TH Shift and SS-Induced Low-Gray Dispersion in AMOLED Displays

Year: 2026

Type: article

Abstract: In this article, we present a voltage-programmed 5T1C pixel circuit based on an amorphous indium–gallium–zinc-oxide (a-IGZO)-only thin-film transistor (TFT) platform for active-matrix organic light-emitting diode (AMOLED) displays. The proposed circuit consists of five TFTs and one storage capacitor (CST), and employs a bottom-gate-biased double-gate driving TFT (DR TFT). A negative bottom-gate voltage (V ${}_{\mathrm {BG}}$ ) shifts the DR TFT transfer characteristic toward the positive-threshold-voltage (V ${}_{\mathrm {TH}}$ ) direction, placing the DR TFT in the enhancement-mode operating regime and enabling diode-connected VTH compensation. The VBG sweep is used as a controllable electrostatic perturbation to modulate the DR TFT characteristics and experimentally evaluate robustness against coupled VTH and subthreshold-swing (SS) variations, rather than as a direct compensation signal during pixel operation. Measured transiently programmed OLED currents under VBG modulations of ±1.0 and ±2.0 V demonstrate suppression of SS-induced low-gray current dispersion. The average LSB error remains below 1 LSB up to 114G and below 5 LSB over the full 8-bit (255G) range. Moreover, the proposed layout achieves a subpixel area of $16~\mu $ m $\times 36~\mu $ m, corresponding to 748 PPI for a 6.3-inch UHD display, supporting high-resolution and low-power a-IGZO-only AMOLED backplanes.

Source: IEEE Journal of the Electron Devices Society

DOI: 10.1109/jeds.2026.3727311