MicroLED v OLED – which one wins?

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Whilst OLED has been the high-end electronic display of choice for a while now, the consumer electronics giants’ war for innovation supremacy continues. And as was evident at CES 2018, a new technology is tipped to battle it out with OLED in the electronics display space.

The concept launch of new MicroLED based displays by Samsung at CES 2018, left consumers curious about the emerging technology and, let’s face it, rumours of a MicroLED based Apple smartwatch have been around for months.

So, should we all think about ditching our brand-new OLED displays for MicroLED? Or is it still further from mass production than we might be led to believe? We look at what the challenge from tech new-comer, Micro-LED, means to OLED.

5 facts about MicroLED

Firstly, let’s look at the facts:

  • As the name implies, MicroLED based displays consist of millions of microscopic LEDs, which form the individual required pixel elements.
  • When compared to contemporary LC displays, MicroLED offers improved energy efficiency, as well as enhanced contrast and response times.
  • From a colour vibrancy perspective, MicroLED has comparable performance to OLED.
  • Today, primarily aimed at small device applications including wearables and smartphones – although notably demonstrated by Samsung’s huge ‘The Wall’ at CES 2018 – MicroLED is based on conventional GaN LED technology. GaN LED offers higher total brightness than today’s OLED technology, as much as 30 times higher if reports are correct, and has higher efficiency in terms of lux/W.
  • MicroLED has been in the research laboratory for years. It might be pretty cool but it’s still in the early stages of development.

MicroLED Pros

MicroLED, just like OLED, is an emissive display technology. Each pixel generates its own light; no backlighting is necessary as required in LCD screen solutions. Emissive display technologies deliver excellent colour and contrast performance, perfect black levels and near-perfect off-angle viewing capabilities; everything LC displays struggle with.

The excitement surrounding the MicroLED development is that it offers all the benefits of OLED, being another emissive technology. However, MicroLED does not rely on organic compounds to deliver the light. This means screen burning, so often criticized by frustrated consumers, is eliminated and a longer device life is secured.

Even slimmer products can also be manufactured meeting device form factor innovation requirements. However, MicroLED does not score on flexibility, compared with OLED, leaving the holy grail of bendable and foldable devices firmly in the OLED market space well in to the future.

MicroLED will deliver on the perfect blacks, vibrant colours and contrast, as well as the near-perfect off-angle viewing. It will be brighter and should be less expensive to manufacture than OLED. However, the argument is still not proven in practice.

MicroLED Cons

Common for many new display technology introductions, the key stumbling block for MicroLED sits in adapting the display manufacturing process.

Fundamentally, there are two alternative ways to manufacture MicroLED displays. The most common route involves growing the LEDs on a wafer, developing a backplane substrate with electronics circuitry and then moving the tiny LEDs from the wafer on to the display electronics. Clearly this requires a fast and accurate automated process. The second method is where the LEDs are grown directly on the display’s backplane, which eradicates the transfer process but limits the size of display as the LEDs are tricky to grow on large substrates.

Perfectly picking and placing millions of microscopic LEDs is a tough challenge, even for fully automated robotic production lines.

For a typical MicroLED based TV screen, there would be literally tens of millions of LEDs required. Each RGB is packaged for a pixel, grouped in modules and these modules make up the screen design; an altogether different proposition for the manufacturing process.

Unsurprisingly, difficulties in pilot production are being reported. The challenge particularly lies in the gap between the pixels, or the ‘pitch size’ as it’s known. With microscopic LEDs, the other parts of the display shrink too and have a limit on how small they can become. In addition, smaller LEDs mean lower levels of light being produced. The LEDs have to increase efficiency to deliver comparable levels of performance to OLED. This drives up the power demand and creates higher heat output; all of which have to be managed.

The future of MicroLED

Reports of successful Apple Smartwatch production in Taiwan using MicroLED in 2018 have so far proven unfounded and display manufacturers continue to focus on bringing the production challenges under control and costs down.

One Taiwan based company’s R&D efforts claim it is taking 10 seconds to transfer and place 200,000 LEDs, which would mean a 5” panel taking approximately 10 minutes to produce. However, the cost for a single smartphone could reach $300 – much higher than the cost of even the top end flexible OLED solution, reinforcing the belief that MicroLED market opportunity may be constrained.

On the other hand, MicroLEDs are ideal for small form factor products and growth potential is presented by MicroLED application in near-eye displays for augmented/virtual reality devices. An exciting area of market development, MicroLED enables the very high pixels per inch (PPI) required for this technology, leading to significant investment by many of the big players. The vision for MicroLEDs could mean the transformation from a typical bulky and power-hungry VR headset to something more akin to a pair of glasses.

MicroLED v OLED – which one wins?

Clearly, OLED in 2018 continues to be the market’s best emissive display technology, already featuring in a range of small and large screen devices from mobile phones to televisions. It is estimated that over 500 million OLED displays were shipped in 2017 and a number of companies, including the pioneer of organic semiconductors, SmartKem, are delivering on the promise of flexible, foldable and even rollable displays with great image quality in the near future.

MicroLED offers some exciting benefits to the competitive consumer electronics world – from vibrant display to longer life – but OLED and its unique promise of flexible display to excite the innovation hungry consumer will undoubtedly keep it at the table for a long time to come yet.

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