Electrodynamics of Charge Balance in Quantum‐Dot Light‐Emitting Diodes

ABSTRACT Efficient quantum‐dot light‐emitting diodes are commonly thought to require balanced electron and hole injection, leading to device designs that suppress electron injection or enhance hole injection. Paradoxically, experimental studies frequently show that increasing electron injection does not compromise efficiency and can even improve it, a contradiction that has remained unresolved. Here, we systematically modulate electron injection by engineering the ZnMgO/Al contact and quantitatively evaluate charge balance in QLEDs. Despite a 3.98‐fold difference in current density between devices with suppressed and enhanced electron injection, both exhibit nearly identical external quantum efficiencies, exceeding that of the control device. We show that this counterintuitive phenomenon originates from electrodynamic redistribution of the internal electric field in the multilayer stacked device architecture. Specifically, enhancing the conductivity of one layer, such as the electron transport layer, reduces its voltage drop and redistributes the electric field toward the hole transport and emissive layers, thereby facilitating hole injection and restoring charge balance. These results uncover an electrodynamic mechanism of charge balance governed by internal field redistribution, challenge the conventional “weak electron” optimization paradigm, and suggest an alternative design strategy—enhancing rather than blocking electron injection—for simultaneously achieving high efficiency, low power consumption, and improved operational stability in QLEDs.