Research Progress on Annealing Strategies for High‐Performance Quantum Dot Light‐Emitting Diodes

ABSTRACT

Quantum‐dot light‐emitting diodes (QLEDs) are increasingly recognized as leading candidate for next‐generation display and solid‐state lighting platforms, owing to their adjustable emissions, elevated quantum efficiencies, and compatibility with large‐area fabrication processes. This work reviews the decisive role of annealing temperature in governing the performance of QLED, organized layer by layer across electron transport layers, emissive layers, hole transport/injection layers, and electrodes in both Cd‐based and Cd‐free (e.g., InP‐based) systems. For Cd‐based quantum dots (QDs), intermediate thermal annealing (100°C–150°C) removes residual solvents and ligands, densifies QD films, improves crystallinity, and optimizes carrier balance, enabling high external quantum efficiencies and long device lifetime. In contrast, InP‐based QLED require a more process‐dependent thermal budget: high‐temperature steps may be used during QD synthesis or interlayer treatment, whereas direct annealing of the QD emissive layer must be limited according to shell structure, ligand stability, and QD/oxide interfaces. Appropriately tailored annealing temperatures and atmospheres for electron transport layers and hole injection/transport layers modulate phase evolution, defect chemistry, conductivity, and interfacial energetics, yielding efficient and stable devices. Future optimization is needed to treat annealing as a distributed, layer‐specific design parameter to achieve QLEDs with high efficiency, long operational lifetime, and manufacturability.