Colloidal quantum dots (QDs) exhibit tremendous potential in display technologies owing to their unique optical properties, such as size‐tunable emission wavelength, narrow spectral linewidth, and near‐unity photoluminescence quantum yield. Significant efforts in academia and industry have achieved dramatic improvements in the performance of quantum dot light‐emitting diodes (QLEDs) over the past decade, primarily owing to the development of high‐quality QDs and optimized device architectures. Moreover, sophisticated patterning processes have also been developed for QDs, which is an essential technique for their commercialization. As a result of these achievements, some QD‐based display technologies, such as QD enhancement films and QD‐organic light‐emitting diodes, have been successfully commercialized, confirming the superiority of QDs in display technologies. However, despite these developments, the commercialization of QLEDs is yet to reach a threshold, requiring a leap forward in addressing challenges and related problems. Thus, representative research trends, progress, and challenges of QLEDs in the categories of material synthesis, device engineering, and fabrication method to specify the current status and development direction are reviewed. Furthermore, brief insights into the factors to be considered when conducting research on single‐device QLEDs are provided to realize active matrix displays. This review guides the way toward the commercialization of QLEDs.

Electroluminescence quantum dot devices (QD‐LEDs) show the promise in the development of future displays. For commercialization, the top emission device structure is more advantageous than the bottom emission device structure to realize the high aperture ratio full color displays. Moreover, it is essential to understand not only the device structure and characteristics of QD‐LEDs but also the challenging issues in inkjet‐printed devices. Here, we demonstrated the world first all inkjet‐printed Cd‐free active matrix QD‐LEDs based on getting over the hurdles of all inkjet printing process. Especially, we have fabricated QD‐LED devices by stacking 4‐soluble layers without intermixing and studied the factors affecting QD efficiency and QD printing and the influence of ETL solvent on QD. Inkjet‐printed QD‐LED devices have achieved 8 cd/A, 70 cd/A, and 8 cd/A current efficiency of red, green, and blue, respectively, on the basis of 250 nits of full white RGB panels. We believe that our work clarifies an encouraging step toward the practical application of Cd‐free based QD‐LED displays.

By optimizing the micro-cavity top-emission QD-LED structures based on InP QDs, 3.2-fold improvement in the efficiency is obtained compared to the bottom-emission device structures.

We demonstrated the world first all inkjet‐printed Cd‐free ELQDs based on getting over the hurdles of all inkjet printing process. Especially, we fabricated EL‐QD devices by stacking 4‐soluble layers without intermixing and have studied the factors affecting QD efficiency, QD printing and the influence of ETL solvent on QD.

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