Abstract
The detailed measurement and characterization of strain-induced performance variations in flexible InGaZnO thin-film transistors (IGZO TFTs) resulted in a SPICE TFT model able to simulate tensile and compressive bending. This model was used to evaluate a new concept, namely, the active compensation of strain-induced performance variations in pixel driving circuits for bendable active matrix arrays. The designed circuits can compensate the mobility and threshold voltage shifts in IGZO TFTs induced by bending. In a single TFT, a drain current of 1 mA varies by 83 μA per percent of mechanical strain. The most effective compensationcircuit design, comprising one additional TFT and two resistors, reduces the driving current variation to 1.1 μA per percent of strain. The compensation circuit requires no additional control signals and increases the power consumption by only 235 μW (corresponds to 4.7%). Finally, switching operation is possible for frequencies up to 200 kHz. This opens a way toward the fabrication of flexible displays with constant brightness even when bent.