Generic low-cost characterization of VTH and mobility variations in LTPS TFTs for non-uniformity calibration of active-matrix OLED displays

Active-matrix organic light emitting diode displays are prone to significant VTH and mobility variations in low-temperature polycrystalline-silicon thin-film transistors. A low-cost characterization of these variations can lead to a practical external calibration and simulation of the display non-uniformity. This paper proposes a generic methodology based on principal component analysis, relying on the display current levels corresponding to applied characterization images. This technique results in simultaneous characterization of the VTH and mobility for the entire active matrix. Measurement results show that taking advantage of spatial correlation leads to 100 times reduction in characterization time with less than 30% relative error.