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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, MoO3 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 MoO3 nanoparticles with an average grain size around 2 nm and successfully achieved MoO3 patterns through direct photolithography by incorporating photosensitizers. Furthermore, QLED devices with the photolithographed MoO3 as the hole injection layer (HIL) were fabricated, and pixel patterns with different shapes were designed and achieved. Compared to QLEDs based on pristine MoO3, the devices with photolithographic MoO3 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. [ABSTRACT FROM AUTHOR]

Inverted perovskite light-emitting diodes (PeLEDs) based on quantum dots (QDs) are some of the most promising candidates for next-generation lighting and display applications. Due to the strong fluorescence quenching caused by zinc oxide, high performance in such inverted devices remains challenging. Here, we report an efficient inverted green CsPbBr 3 QDs LED using an emitting buffer layer. Ultrathin CsPbBr 3 QD emitters act as the buffer layer to reduce the interface luminescence quenching reaction at the ZnO/upper emitting layer interface, increasing the probability of exciton recombination within the emissive layer and regulating the charge transport, leading to effective carrier recombination. The resulting device exhibits an external quantum efficiency of 13.1%, enhanced by about 4.7 times compared with that without a buffer layer device. This work provides a path to fabricating high-performance inverted PeLEDs.

A solution-processed molybdenum oxide (MoO x ) as the hole injection layer (HIL) by doctor-blade coating was developed to improve the efficiency and lifetime of red-emitting quantum-dot light-emitting diodes (QD-LEDs). It has been demonstrated that by adding isopropyl alcohol into the MoO x precursor during the doctor-blade coating process, the morphology, composition, and the surface electronic structure of the MoO x HIL could be tailored. A high-quality MoO x film with optimized charge injection was obtained, based on which all-solution-processed highly efficient red-emitting QD-LEDs were realized by using a low-cost doctor-blade coating technique under ambient conditions. The red QD-LEDs exhibited the maximum current efficiency and external quantum efficiency of 16 cd/A and 15.1%, respectively. Moreover, the lifetime of red devices initializing at 100 cd/m 2 was 3236 h under ambient conditions, which is about twice as long as those with a conventional poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) HIL. Large-area QD-LEDs with 4 in. emitting areas were fabricated with blade coating as well, which exhibit a high efficiency of 12.1 cd/A for red emissions. Our work paves a new way to the realization of efficient large-area QD-LEDs, and the processing and findings from this work can be expanded into next-generation lighting and flat-panel displays.