A microLED is a next-generation flat-panel display technology based on an array of microscopic light-emitting diodes or LEDs to form individual pixel elements. Sometimes referred to as mLED or µLED, it is also a specific type of self-emissive display with characteristics and advantages that are generally similar to OLED display technology.
The technology was first invented in 2000 by a team of researchers spearheaded by Hongxing Jiang and Jingyu Lin while they were at Kansas State University. Sony Corporation demonstrated the first microLED displays before the public in 2012, but commercialization plans did not materialize due to their higher price tags.
Barriers to technology and production prevented commercialization. There was a need to develop and discover more innovations to advance the underlying technologies, improve production efficiency, and drive down manufacturing costs. Several companies have introduced conceptual products since then.
For example, Samsung showcased its the 146-inch µLED it called The Wall at CES 2018, while LG Electronics demonstrated a 173-inch display during IFA 2018. The Crystal LED Display from Sony eventually began available starting September 2019 while Samsung announced it began shipping The Wall to the international in October 2019.
More manufacturers are looking forward to develop microLED display technology due to its superior advantages over OLED display and LCD technologies. Apple Inc. has started developing its own implementation in-house since 2018.
The Pros: Advantages and Applications of MicroLED Display Technology
Several industry analysts and technology enthusiasts believe that microLED would become a next-generation technology that could compete head-on against or totally replace IPS LCD and OLED display technologies.
But what exactly is microLED? For starters, it involves using microscopic light-emitting diodes or LEDs and fitting them into a single pixel. Earlier prototypes have demonstrated three microscopic LEDs per pixel. The fact that display panel uses LEDs means that it does not require LED backlighting unlike LCD technologies. LEDs are self-emissive.
Nevertheless, one of the primary selling points and thus, advantages of this technology is that it has the positive characteristics of OLED minus the drawbacks associated with shorter lifespan due to screen burn-in and limited luminosity.
Shares the Same Advantages of OLED and other Emissive Display Technologies
OLED has increasingly become a preferred display technology since 2008 among manufacturers and consumers. The display technology started appearing in flagship devices such as the Galaxy Series of smartphones from Samsung, and other companies have featured the same technology on their high-end devices. However, improvements in productions allowed manufacturers to use OLED displays even on their mid-range product lines.
There are several reasons to choose OLED over in-plane switching or IPS LCD technology. These include better contrast ratio, higher response time, wider viewing angle, energy efficiency, slimmer screen profile, and flexibility. OLEDs usually produce a more superior image quality when compared to LCDs based on in-plane switching while allowing manufacturers to introduce different form factors to include edge-to-edge displays and curved screens.
Take note that OLEDs and even QLED displays are self-emissive displays. Light comes directly from the individual organic LEDs unlike LCDs that require LED backlighting for colors produced by individual pixels to become visible. The same is true for microLED.
Individual LEDs in LED-based display panels can be turned on and off. Both display technologies are capable of producing deep blacks and thus, have a wider contrast ratio than panels based on LCD technology. Because each pixel can be controlled individually, they can display a completely different color to the one next to it, thereby offering better color control, more accurate image representation, and possibly better refresh rates than LCDs.
Nevertheless, microLED shares the aforesaid advantages of OLED, especially when compared to IPS LCD. The display technology has been assumed by researchers and industry players to compete with other display technologies in the market. Hence, in the future, it could be featured in devices ranging from televisions and laptops to smartphones and tablet computers. And there is a strong reason to vouch for it over OLEDs and IPS LCDs.
Addresses the Drawbacks or Limitations of OLEDs while Competing with IPS LCD Technology
On paper, OLEDs are considerably superior to IPS LCDs. However, the market share for liquid crystal display remains sizeable. Some manufacturers and consumers still prefer LCDs because OLED displays have two major drawbacks: short lifespan due to susceptibility to screen burn-ins, uneven aging because of the difference in the degradation rate of blue, red, and green organic diodes, and fragility due to the higher sensitivity of organic diodes to moisture when compared to inorganic hardware components.
Take note that microLED does not have the aforesaid disadvantages. The display technology banks primarily on using inorganic light-emitting diodes. These materials are more durable and have a longer lifespan than organic light-emitting diodes. The degradation rate of each pixel is almost uniform. Hence, from the standpoint of a consumer, devices featuring this tech would have longer usability than their OLED counterparts.
Another advantage of microLED over OLED is that it is theoretically more energy efficient. It is also compatible with smaller chips, thus enabling the manufacturers to expand its capabilities or improve its performance. Note that large chip size is more ideal for OLED displays to help achieve a longer lifespan and higher luminance. The technology also has better brightness. OLEDs have an inherent peak brightness of up to 1000 nits. Meanwhile, microLED prototypes have demonstrated general brightness of 4000 nits, and it can peak further to 10000 nits with better engineering.
It is also worth noting that this emerging display technology can support thin and bezel-less display screens with perfect viewing angle similar to OLED. It also supports modularization. These characteristics make it a viable candidate for use both mobile devices and large TVs and outdoor displays.
The Cons: of MicroLED Display Technology
Challenges in Manufacturing Processes, Costs, and Mass Production
The concept behind microLED display technology is simple: use small-sized LEDs to form individual pixel elements. However, the process remains challenging. Manufacturing currently presents the primary challenges in mass-producing and commercializing this next-generation display.
For example, it would be difficult to shrink particular light-emitting diodes without compromising their performance. Doing so would mean reducing the intensity of light it produces. Solving the trade-off between size and performance would require driving them further, increasing their efficiency, or achieving both. Driving them further would consume more energy and produce more heat. Making them more efficient means identifying and introducing new technologies and processes in manufacturing individual LEDs.
Another issue is the need to address the gaps or pitch size between microscopic LEDs and the pixels. It is essential to highlight the fact that circuitry and other components can only get so small. The current conventions in circuit design and engineering do not support fully the production of microLEDs of varied sizes.
Producing microscopic LEDs and associated components in large volumes is also an issue. Manufacturers need to ensure that there is no variation in brightness and that assembling them is in perfect alignment. As an illustration, take note that producing a microLED display with a 4K resolution would require 25 million microscopic LEDs.
LCD Based on Mini-LED is a More Practical Alternative to Emissive Displays
Manufacturing issues translate to production cost and feasibility for mass production. Hence, another disadvantage of microLED display is that it is currently impractical to produce when compared to IPS LCD and OLED displays. However, there is another alternative.
Several manufacturers and researchers have positioned mini-LED as another option. Note that this is not an actual display technology. Rather, it is a backlighting scheme used in panels based on LED-backlit LCD technology. More specifically, it involves using small-sized light-emitting diodes to illuminate LCD panels to improve local dimming capabilities and increase the contrast ratio. Hence, the technology inherits the advantages of LCD.
It is worth mentioning that mini-LED has several advantages that can rival and outperform OLED and microLED. For example, when used as a backlighting scheme for an in-plane switching or IPS LCD, it can provide deep blacks or better contrast ratio, superior brightness, and unrivaled outdoor visibility.
It would take several years before the display technology becomes available in the market. Most televisions are still based on IPS LCD technology while premium TVs and mobile devices sport OLED panels. There is also an emerging market for QLED display panels from Samsung.
Summary of the Advantages and Disadvantages
The following are the advantages of microLED display technology:
- It is a self-emissive display that does not require backlighting, thus producing a considerably even brightness across the screen.
- Pixels can be turned on and off individually to produce deep blacks and wider contrast ratio similar to OLED display panels.
- Better color control, more accurate image representation, and possibly better refresh rate because each pixel can be controlled individually.
- General brightness is around 4000 nits, but future iterations can produce a brightness of up to 10000 nits through better engineering.
- Has a longer lifespan than OLEDs or in other words, it does not suffer from screen burns due to different degradation rates of pixels.
- It can support thin panels, thin to zero bezels with wide viewing angles, and modularization to make it a universally applicable display tech.
The following are the disadvantages of microLED display technology
- There are manufacturing challenges needed to overcome to commercialize and produce microLEDs for the mass market.
- Costs remain high due to the manufacturing challenges, thus making LCD and OLED technologies more economical.
- There is also a need to resolve the issue related to pitch size and the introduction of new conventions in circuit design and engineering.
- Consistency in producing millions of microscopic LEDs and assembling them in a single display panel should also be addressed.
FURTHER READINGS AND REFERENCES
- Horn, R-H., Chien, H-Y., Trantair, F-G., and Wuu, D-S. 2018. “Fabrication and Study on Red Light Micro-LED Displays.” IEEE Journal of the Electron Devices Society. 6: 1064-1069. DOI: 1109/jeds.2018.2864543
- Huang, Y., Hsiang, E-L., Deng, M-Y., and Wu, S-T. 2020. “Mini-LED, Micro-LED, and OLED Displays: Present Status and Future Perspectives.” Light: Science & Applications. 9: 105. DOI: 1038/s41377-020-0341-9
- Konsyse. 2020. “Difference Between Micro-LED and miniLED.” Konsyse. Available online
- Moore, S. K. 2019. “microLED Displays Expected in 2020: The Last Remaining Hurdle is Mastering Mass Production.” IEEE Spectrum. 56(8): 8-9. DOI: 10.1109/MSPEC.2019.8784111