Direct Optical Patterning of MoO₃ Nanoparticles and Their Application as a Hole Injection Layer for Solution-Processed Quantum Dot Light-Emitting Diodes

Abstract

Quantum dot light-emitting diodes (QLEDs) are emerging as promising contenders for next-generation display technology owing to their remarkable performance. In extensive research on QLEDs, MoO 3 is commonly used as a replacement for the acidic hole injection material PEDOT:PSS to avoid acid corrosion of the indium tin oxide (ITO) electrode, thus preventing degradation of QLED performance. The advantages of solution-processed QLEDs make them an attractive option for large-scale production. Nowadays, achieving pixelation is still a critical step in the commercialization of QLEDs. In this work, we synthesized ultrafine MoO 3 nanoparticles with an average grain size around 2 nm and successfully achieved MoO 3 patterns through direct photolithography by incorporating photosensitizers. Furthermore, QLED devices with the photolithographed MoO 3 as the hole injection layer (HIL) were fabricated, and pixel patterns with different shapes were designed and achieved. Compared to QLEDs based on pristine MoO 3, the devices with photolithographic MoO 3 exhibited a higher external quantum efficiency (EQE) and brightness. We believed that this work could establish a technological foundation for the development of high-resolution QLED displays.