Micro Light-Emitting Diode Pixel Circuit Based on Indium-Gallium-Zinc Oxide Thin-Film Transistors Using Pulse Width Modulation

Herein, we proposed a micro light-emitting diode (μ LED) pixel circuit based on indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs). Pulse-width modulation (PWM) was utilized to overcome the wavelength shift of the μ LEDs. The proposed pixel circuit compensated for the threshold voltage (VTH) of the driving TFTs using a source-follower structure and the variation of μ LED forward voltage (Δ VLED). The proposed μ LED pixel circuit successfully expressed 256 gray levels using PWM. In addition, the proposed circuit exhibited a normalized luminance error rate lower than 4.8% under VTH variation (Δ VTH) of ±1.0 and Δ VLED of ±0.4 V. Consequently, the proposed μ LED pixel circuit based on IGZO TFTs successfully expressed gray levels using PWM and operated stably under Δ VTH and Δ V LED.