The Complex Value Proposition of Micro-LEDs

Article By : John Walko

Micro-LEDs are being over-hyped as a potential replacement for OLEDs, LCDs and quantum dot based displays, IDTechEx is warning.

Micro-LED displays are being over-hyped as a potential replacement for OLEDs, LCDs and quantum dot based displays, market research group IDTechEx (Cambridge, UK) is warning. The firm’s report focuses on replacing other technologies in the displays market but also considers creating a new market.

The IDTechEx researchers note that the self-emissive LED-based displays, often being considered as direct replacement for OLED displays, may not meet all the value propositions using the current technology, nor the cost expectations.

Micro LED pixels are comparatively smaller than LED pixels.

In the past, the researchers also suggested that gaps in the current supply chain and manufacturing capabilities may, on the one hand, be seen as hindering progress, yet on another level are generating an opportunity.

As the name implies, Micro-LEDs use much smaller LED chips than its predecessors and the displays are made of self-emissive inorganic LEDs, acting as subpixels. These LEDS are generally in the micrometer range, without package nor substrate, and are transferred in a way different from traditional pick-and-place techniques.

The most often cited value propositions for them are a wide color gamut, high luminance, low power consumption, high stability and long lifetime, wide view angle and high dynamic range.  Other advantages are said to be a fast refresh rate, transparency, seamless connection and sensor integration capability.

Micro-LED screens can also be made extremely thin and can achieve wide viewing angles. In fact, the LEDs themselves directly create the image, and the picture created is composed of individually addressable LEDs, making a micro-LED work more like an OLED does.

But, according to Xiaoxi He, principal Research analyst at IDTechEx, on their current status, the advantages might be offset by high costs, at least in some specific applications.

For example, the report notes the improved lifetime of micro-LEDs in mobile phone applications. But many users change their handsets every 2 to 3 years, making longer screen life less attractive when considering the additional costs.

And when it comes to potential improvements to power consumption, the analysts note that the EQE’s (external quantum efficiency) of really tiny micro-LEDs are low, and final device power consumption can turn out to be much higher; similarly, very small micro-LEDs cannot yet be considered as mature and thus it can be costly and difficult to achieve really high resolution in these emerging displays.

“Based on the current status, some value propositions may not be realistic or significant for specific applications — again related to higher costs, He told EE Times.

micro-LEDsThe analysts identify eight potential applications where the displays might replace existing technologies over the medium term. They include AR/MR, VR, large video displays, TVs and monitors, automotive displays, mobile phones, smartwatches and wearables, and tablets and laptops.

Still focusing on the replacement opportunity, the report notes that LCD displays that currently dominate the market, are applied in almost all displays under 65”. The researchers stress that LCDs have their intrinsic limitation to go to larger sizes.  Meanwhile OLEDS are increasingly taking a larger share in the market, notably in news smartphone models.

OLED panel manufacturing is dominated by South Korean companies, both when it comes to production capacity and technology maturity, upstream materials and equipment as well as downstream applications.   For the latter, Samsung’s small to medium-size OLED panels are firstly supplied to other Samsung divisions, while LGD’s larger –sized OLEDS panels first find their ways into LG’s TVs.

Another already fairly competitive market is quantum dot (QD) technology, mainly using its photoluminescence feature.  By applying QD films in the LCD structure, the colour gamut can be significantly improved, and such displays are catching up fast, the researchers suggest.

He stresses that each technology has its particular features for end users.  The  accompanying graph, clearly show that some of the value propositions can be provided by alternatives. But, “there are some value propositions unique for Micro-LED displays.”

And she suggests that whether Micro-LED displays can replace OLED or not, at least in the short to medium time scale, “is a very application–dependent question.”

For the front plane of a typical Micro-LED display, the cost is particularly dependent on the number of LEDs needed, instead of the area. This is different when it comes to OLEDs and LCDs. Which is why “fabricating a smartphone with the same resolution as a TV may result in a similar cost projection, rather than orders of magnitude lower expectation.”

When it comes to creating a new display market, this calls for features that cannot or can hardly be enabled by alternatives. Typical examples offered in the report include displays with customized shapes and displays with sensor integrations. “If I had to choose one category likely to make a really significant impact in the medium term, it would be customizable displays targeting portable devices, “ Dr He told EE Times

And, as previously noted, micro-LEDs displays at this stage are difficult to make, and thus   expensive. For this to improve and make the segment cost effective, innovation will be needed in a number of important areas. For instance, processes that can scale up manufacturing would seem essential, as would improvement in areas such as chip transfer, repair, inspection and light management techniques. “There certainly are numerous challenges before we can talk about any kind of volume manufacturing of Micro-LED based displays. And when it comes to testing, it is vital that the companies involved get it right when it comes to zero defects,” said Dr He.

The industry is likely to come up with different technology approaches for volume manufacturing for different end use applications, she adds. “For instance, the big companies involved seem to be deploying different chip transfer processes, some based on micro  pick and place techniques or laser related approaches”.

As to current availability of products using the technology, in the TV sector, leading names such as LG, Sony and Samsung have already demonstrated models with Micro-LED screens, and others are believed to have prototypes in various stages of development.

For instance, at last November’s virtual CES, Samsung showed a 110” model capable of displaying four 55” HD images at the same time. (Yours for about $156,000).

The 110” model, Samsung notes, was made possible through the development of “cutting edge surface mount technology — along with a new production process derived from our semiconductor business. “

The company says the same innovation will allow it to bring to market smaller, cheaper models that are scheduled for later this year.

For the moment Sony is focusing on the commercial sector with its Micro LED products, which it calls Crystal LED. Other companies are developing products for the opposite end of the size scale, for instance smart glasses to project images, similar to head-up displays.

And Apple is reported to be developing its own in-house Micro-LED displays for use in mobile devices that eventually will replace existing OLED-based screens.

This article was originally published on EE Times.

John Walko is a technology writer and editor who has been covering the electronics industry since the early 1980s. He started tracking the sector while working on one of the UK’s oldest weekly technology titles, The Engineer, then moved to CMP’s flagship UK weekly, Electronics Times, in a variety of roles including news deputy and finally editor in chief. He then joined the online world when CMP started the EDTN Network, where he edited the daily electronics feed and was founding editor of commsdesign.com (which, over the years, has become the Wireless and Networking Designline). He was editor of EE Times Europe at its launch and subsequently held various positions on EE Times, in the latter years, covering the growing wireless and mobile sectors.

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