Cathode area reduction for superior gate modulation and performance enhancement in quantum dot light-emitting diodes

Three-terminal light-emitting diodes (LEDs) hold significant application prospects, though they still face several limitations. One of its challenges is that the electrostatic screening effect diminishes the external electric field penetration, thereby compromising devices’ performance. This electric field shielding effect significantly weakens the gate control ability of three-terminal LEDs, resulting in a decrease in device performance and functionality. To deal with this issue, we proposed a strategy to enhance the gate electric field control effect on quantum dot light-emitting diodes (QLEDs) by reducing the electrode area between the anode and the gate electrode. Concurrently, we investigated the optoelectronic properties of gate-tunable QLEDs under varying electrode areas and gate voltages. The experimental results show that under the same gate voltage, the smaller the active area of the gate-tunable QLEDs, the greater the improvement in their luminance and external quantum efficiency. The simulation results indicate that the smaller the electrode area, the weaker the shielding effect on the external electric field. In summary, the strategy we proposed, which weakens the shielding effect of the external electric field by reducing the electrode area, shows great potential in the field of electric field modulation for three-terminal devices.