Display is a ubiquitous medium for visual-information transmission and interaction. Owing to the rapid development of the information age and the continuous improvement of living standards, display technology is being constantly developed to satisfy the requirements for high-quality image display. The rapid progress of artificial intelligence in recent years has resulted in increasingly intelligent display technologies that can adapt to different scenarios while constantly enhancing people’s visual experience and realizing human-computer interaction. The introduction of virtual/augmented reality (VR/AR) and other technologies has posed new challenges to display resolution and brightness. The current mainstream light-emitting diodes (LEDs) and liquid-crystal displays (LCDs) can no longer fulfill these requirements; hence, microdisplay technology must be further developed urgently to satisfy the requirements of display development. The current microdisplay technology is dominated by micro-light-emitting diodes (Micro-LEDs) and silicon-based drive organic electroluminescent diodes (Micro-OLEDs). However, the size effect of Micro-LEDs and the sidewall effect caused by their miniature size limit their light-emitting efficiency. Furthermore, they must be transferred in large quantities and their processing is demanding. Micro-OLEDs are limited by their ultrafine mask plate as well as precise positioning evaporation and harsh conditions, thus significantly limiting their cost.

Quantum dots, as a nanoscale semiconductor light-emitting material used in display technology, offer many unique advantages, such as adjustable bandgap, high quantum yield, high color purity, and low power consumption. Quantum-dot light-emitting diodes (QLEDs) are a novel type of quantum-dot-based optoelectronic device introduced in the 1990s. After their development for almost 30 years, their luminescence has improved significantly, and their current external quantum efficiencies of red, green, and blue three-color luminescence exceed 20%. Owing to the excellent characteristics of quantum dots, their luminous efficiency is almost unaffected by the light-emitting pixel size. Thus, the LED size effect and sidewall effect are avoided, which renders them an excellent microdisplay material. Quantum-dot microdisplay technology has been extensively investigated in recent years. Currently, various patterning and full-color modes have been used to realize high-resolution quantum-dot light-emitting devices, and the display resolution has exceeded 10000 pixel/inch. However, few mature quantum-dot microdisplays have been developed. Moreover, the performance and pixel contagion of high-resolution quantum-dot devices and the associated driving backplanes necessitate further investigation. Therefore, one must summarize the results of the current research, clarify the existing challenges, and consider the future development trends.

Quantum-dot microdisplay technologies for patterning array devices have been developed significantly, including photolithography, inkjet printing, transfer printing, self-assembly technologies, laser direct writing, and optical microcavity technologies. These advances are comprehensively summarized herein in Figs. 1?4 and 6?9. In 2020, Xu et al. proposed a sacrificial-layer-assisted pattern-formation method to achieve a full-color passive matrix QLED device with a pixel density of 500 pixel/inch. In the same year, Kang et al. developed a method to pattern quantum dots with light-driven ligand cross-linkers, which successfully generated a full-color quantum-dot pattern with a resolution of 1400 pixel/inch. In 2023, Chen et al. demonstrated an electrohydrodynamic (EHD) printing method for preparing a dual-color (red and green) bottom-emitting QLED device with a resolution of 500 pixel/inch. In 2015, Hyeon et al. of the Institute for Basic Science in the Republic of Korea performed gravure transfer printing to prepare pixel arrays with dimensions of up to 2460 pixel/inch, which achieved an almost 100% transfer yield and maintained the integrity of the pixel shapes. In 2021, Chen et al. of TCL, Sun et al. of the Southern University of Science and Technology, and Zhang et al. of Peking University developed a novel selective electrodeposition (SEPD) technique to achieve full-color, large-area patterned films of quantum dots with resolutions greater than 1000 pixel/inch and successfully fabricated high-performance QLED devices. In 2022, Li et al. of Fuzhou University developed quantum-dot light-emitting diodes with an ultrahigh pixel resolution of 9072?25400 pixel/inch using the Langmuir?Blodgett (LB) assembly technique combined with transfer-film technology. In 2022, Sun et al. of Tsinghua University proposed a femtosecond laser direct writing strategy (FsLIFT) to deposit chalcogenide quantum dots (PQDs) using laser-induced Marangoni; additionally, they prepared high-resolution patterns of PQDs with a minimum linewidth of 1.58 μm by adjusting the laser power and exposure time. In 2021, Chen et al. of the Southern University of Science and Technology developed a color-converting cavity to achieve high-resolution pixelated luminescence and adjusted the thickness of the phase-tuned layer via lithography. They successfully converted white-light quantum-dot luminescence into red, green, and blue light, thereby realizing a full-color luminescent device with a high density of pixel density of 1700 pixel/inch.

Advances in display technology will determine the diversification and intelligence of visual-information presentation, and microdisplay technology will enable virtual augmented reality. Quantum dots, as a unique miniature light-emitting unit, offers a unique potential in microdisplay technology and is a strong contender for the next generation of microdisplay products. Therefore, mature patterning and full-color technology are key; additionally, the performance issues of patterning devices and drivers must be addressed. In summary, the existing problems and challenges of quantum-dot microdisplay technology should be summarized based on the progress of existing work, and its further development should be considered to further advance the field.