Blog: Small displays, big future

17 July 2019

microLEDs are set to disrupt OLED in fast-growing areas like wearables and augmented reality

One of the key specs of any product with a screen is the type of technology the display uses: is it LCD (liquid-crystal display) or OLED (Organic Light Emitting Diode)? Whilst most TVs and smartphones still use LCDs (backlit by traditional LEDs), OLED is the technology of choice for high-end products. Because they don’t have to be backlit, OLED displays give much more control over contrast, so that blacks are truly black. And the cost of OLED displays has fallen dramatically in recent years.

These displays can be found in TVs from the likes of Sony, LG and Philips, and smartphones such as Samsung’s Galaxy S9 and Apple’s iPhone X, as well as the Apple Watch.

But for small displays, there is new competition for OLED in the form of another technology: microLEDs. These are microscopic light-emitting diodes: essentially very small LEDs.

According to IHS Markit Micro LED Display Technology & Market report:

“The global market for microLED displays is expected to grow to 15.5 million units in 2026 as steep declines in manufacturing costs make the emerging technology suitable for the mass market.”

Source: IHS Markit

microLEDs offer higher brightness and higher efficiency than OLED – which means more light for less power. Big display manufacturers have shown an interest in applying microLEDs to categories such as wearables, but the big hurdle until now has been the production costs. Not anymore.

The traditional pick-and-place technology used for other LEDs was difficult to apply to microLEDs because of their tiny dimensions – and it’s only getting tougher as demand grows for sharper displays with higher pixel density.

By using unique materials technology, Plessey has made microLEDs much more efficient to produce. Plessey has created microLEDs made from gallium nitride on a substrate of silicon (GaN-on-Si), instead of the usual sapphire. Plessey’s disruptive IP protected GaN-on-Si technology enables the creation of ‘monolithic’ microLEDs – with multiple emitters on a single chip. This means smaller pixel pitches, larger emitters, and – thanks to the unique light-emitting properties of GaN-on-Si – better contrast too.

Plessey showcased a World’s first prototype earlier this year at Display Week in San Jose. The microLED display features an array of 1920×1080 (FHD) current-driven monochrome pixels on a pitch of 8 microns. Each display requires more than two million individual electrical bonds to connect the microLED pixels to the controlling backplane. The Jasper Display Corp eSP70 silicon patented backplane provides independent 10-bit single colour control of each pixel. Bonding a complete LED wafer to a CMOS backplane wafer, incorporates over 100 million micro level bonds between the wafers.

So, while OLED may reign for some years to come for larger displays such as TVs, Plessey’s advances are making microLEDs a serious competitor to OLED for smaller displays. Small displays have a big future: emerging markets such as wearables, head-up displays (HUDs), and augmented and mixed reality (AR and MR) are set to be huge in the years to come, creating a market worth tens or hundreds of billions.

AR may seem niche right now, but it’s making big strides and is set to become more commonplace in areas as diverse as gaming, education, architecture and everyday life. AR enhances the world around you, from navigation by car, bike or foot; task assistance when the flat-pack furniture gets too much; or when you want to try out a new hairstyle without the commitment.

With their high precision and continued high-levels of brightness even against daylight, microLEDs lend themselves to these kinds of applications. And Plessey’s unique monolithic approach to producing microLEDs means they can be built on a CMOS silicon backplane, so standard circuitry can be easily integrated – another real advantage in the high-tech application areas this technology is aimed at.

As these new tools become a bigger part of our lives, we’re going to see more and more microLED technology driving them, making new experiences possible.

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