Measurement and Modeling of Electron and Hole Injection Dynamics in Quantum-Dot Light-Emitting Diodes: Quantifying Temperature-Dependent Charge Imbalance

The development of quantum-dot light-emitting diodes (QLEDs) has been hindered by an incomplete understanding of their charge injection dynamics. This study systematically investigates electron-hole injection in red, green, and blue QLEDs using electrically pumped transient absorption and time-resolved electroluminescence technologies. Temperature-dependent measurements between 140 and 298 K reveal weak electron injection enhancement versus strong hole injection improvement as temperature increases. Therefore, lower temperatures exacerbate charge imbalance, increasing electron accumulation in quantum dots during the operation. We develop quantitative models using space-charge-limited current and thermionic emission theories for electron and hole injection, respectively, establishing a universal framework for QLED operation. These findings provide critical insights for optimizing the charge balance and device performance in QLEDs.