Electronic Structural Insight into High‐Performance Quantum Dot Light‐Emitting Diodes

Quantum dot light-emitting diodes (QD-LEDs) are highly promising light sources with excellent figures of merit. Although great successes have been achieved in elevating some key parameters to an ideal level, QD-LEDs with superior performance in all aspects have rarely been realized. Herein, by exploring crystalline structure-dependent electronic properties, it is shown that QD-LEDs can simultaneously exhibit high external quantum efficiency, roll-off-free under high brightness, and dramatically improved operational stability. This improved performance stems from the crystal phase engineering of QD. Reduced structure symmetry in the wurtzite phase introduces an unneglectable internal crystal field compared with the zinc-blende one, which raises both the conduction and valence band energy levels, thus, facilitating a more balanced charge injection. The crystal phase-optimized superior-comprehensive performance in the QD-LED offers a novel degree of freedom for device engineering and promotes commercial applications for the upcoming display and illumination technologies.