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 V_TH 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 V_TH 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.