Electronic and Excitonic Processes in Quantum Dot Light-Emitting Diodes.

A modified Langevin model has been proposed to study the electronic and excitonic dynamic processes in quantum dot light-emitting diodes (QLEDs), and the electroluminescence onset processes of the QLEDs under different charge-injection conditions have been explored. The simulation results are in good agreement with experimental curves, confirming the feasibility of this model. It is demonstrated that the formation of an exciton on the quantum dots (QDs) with one electron injected first followed by one hole is much more effective than that with the reverse sequence. That is, charging a QD with one electron first is more favorable for device performance enhancement, which is attributed to the low (high) Auger recombination rate of negative (positive) trions of commonly used type I QDs. Additionally, we demonstrate that enough electron injection is one of the prerequisites for high-performance QLEDs based on these type I QDs.