Tuning the threshold voltage of low voltage organic thin film transistor using light illumination

High and random voltages are big challenges for practical applications of organic thin film transistors (OTFTs). Herein, a route to achieve devices with both low operating voltages (V_op) and tunable threshold voltages (V_TH) was proposed. The V_op was reduced to be less 3 V without lowering the mobility and the ratio of on/off current using a 30 nm Al₂O₃ insulator film fabricated by atomic layer deposition technology. And the V_TH was tuned from -1.7 V to 3.8 V by using light illumination combined with voltage pulse on gate electrodes. The tuning range is nearly twice of the operating voltage. And the tuning process is highly reversible. Uniform V_TH of OTFTs can be obtained without changing process or materials.