Unlocking the Potential of Large-Area InP-Based Quantum Dot Light-Emitting Diodes Through Blade-Coating

Quantum dot (QD) light-emitting diodes (LEDs) are attractive candidates for next-generation displays due to their high efficiency, brightness, wide color gamut, and solution processability. Large-scale solution-processing of electroluminescent QLEDs poses significant challenges, particularly concerning the precise control of the active layer's thickness and uniformity. These obstacles directly impact charge transport, leading to current leakage and reduced overall efficiency. Blade-coating is a prevalent and scalable solution processing technique known for its speed and minimal waste. Additionally, it allows for continuous "roll-to-roll" processing, making it highly adaptable in various applications. Furthermore, it is necessary to find a more environmentally friendly alternative to the toxic cadmium-containing active layer composition. In this study, we focus on indium phosphide (InP)-based all-blade-coated QLEDs. The blade speeds significantly influence the thickness and morphology of active thin films. The blade-coated QD thin film reached 25 nm thickness and 5.1 nm root mean square height roughness at optimized speed, comparable to the spin-coated films. We further measured the photoluminescence quantum yield (PLQY) of the active thin film to guide improvements in the external quantum efficiency (EQE) of QLED devices. We aim to transfer existing knowledge to demonstrate the potential for the large-area blade-coating processing technique, emphasizing exploring the relationship between processing parameters, thin film structure, and device performance. This approach addresses current limitations and paves the way for more efficient, sustainable, and scalable QLED technologies.