MicroLED, And How It Wants To Be The Successor Of OLED

It began at CES 2018, when Samsung revealed a wall-sized TV it calls "The Wall." Using a technology called 'MicroLED', it was the first brand-new display technology to be commercialized in more than a decade.

As a successor of OLED, MicroLED uses a similar technology but different implementation.

Going back to display history, TFTs and then LCDs were once desirable. But in the modern days, the technologies are regarded as old. This design creates a bulkier appearance which can also cause uneven brightness, color challenges and other problems.

OLED (Organic LED) on the other hand, uses self-emissive lighting. What this means, each pixels can emit their own light. As the name suggests, it emits light rather than blocking it like LCD. Using red/green/blue/white indicator lights everywhere, the advantages include: the ability to create perfect black color by turning off individual pixels, and creating more outstanding colors. Because of its design, OLEDs are more compact and than its bulkier LCD counterpart, allowing devices to be thinner and lighter.

The main disadvantage of OLED however, is age. Because they are built with organic compounds, over time, the pixels will die off eventually. There's also a chance that some of the compounds will lose luminance more quickly than others, creating an uneven picture, potentially making OLEDs a problem over the long term.

This is where MicroLED wants to be: taking the advantages of OLEDs, but without relying on organic compounds.

MicroLED here also uses self-emissive technology, making it able to create pitch black and great colors. But without using organic compounds, MicroLED panels can be even thinner and capable of delivering wider viewing angles.

This is possible because unlike OLEDs, MicroLEDs are based on conventional GaN LED technology, which offers far higher total brightness (as much as 30 times more than OLED), and a higher efficiency in terms of lux/W. This is also the reason why MicroLEDs don't suffer the short lifetimes of OLEDs.

MicroLED History

The development of MicroLED has been made after years of research. Initially the technology was invented in 2000 by the research group of Hongxing Jiang and Jingyu Lin of Texas Tech University while they were at Kansas State University.

After the first success in delivering electrical injection of microLEDs based on InGaN semiconductors, several other groups started engaging the concept. Then quickly, various on-chip connection schemes of microLED pixel arrays have been employed by III-N Technology, Inc., allowing for the development of single-chip high voltage DC/AC-LEDs. This was made to address the compatibility issue between the high voltage electrical infrastructure and low voltage operation nature of LEDs and high brightness self-emissive microdisplays.

MicroLED was initially meant for small displays and smartphones, but the technology was first introduced on televisions because they require less pixel density.

Lower pixel density means manufacturers won't have to pack as many sub-pixels into the screen to create great display. The lower the pixel density, the easier it is to manufacture a MicroLED set.

Comparing MicroLED And OLED

MicroLEDs share the same advantages of OLEDs, like low latency, high contrast ratio and high color saturation among others. But the most notable, minus the short lifespan.

MicroLEDs can also be a lot brighter than other types of displays, since it relies on LEDs for its light source. This extreme brightness is its main advantage since it allows manufacturers to create better-looking pictures than OLEDs can ever do.

And because MicroLEDs can be created using individual parabolic mirror behind the LED that reflects all of the light toward the viewer, this creates a better brightness vs. power efficiency, improving battery life and lower electricity bills.

It's also thinner and capable in keeping picture quality in a much longer time.

But manufacturing is arguably the most important MicroLED disadvantages.

Manufacturers can produce a single OLED display packed with millions of subpixels in one single step. The result is one outstanding display with an infinite contrast ratio, perfect blacks with a wide viewing angles.

On the other hand, MicroLED that relies on one subpixel produced at a time, is much more challenging to produce. When the technology first emerged, the greatest manufacturing robots weren't capable in making the manufacturing process much simpler.

Here is the reason: MicroLEDs are literally tiny LEDs that are made one at a time. They are then packed and put together into a display using robots that pick and place each of them one at the time, into smaller substrates. Those substrates are then assembled to create one final display.

Then there is the challenge in calibrating the LEDs to deliver the same color controls. Without proper calibration, MicroLED displays won't generate good pictures, let alone surpassing OLEDs.

So here, MicroLED and OLED have their fair share of advantages and disadvantages, which could ultimately translate to some companies deciding to stick with OLED and others opting for MicroLED.

Until people can overcome manufacturing challenges, OLED still has a clear advantage.

Other than Samsung, in March 2018, it was reported that Apple have about 300 engineers devoted to in-house development of MicroLED screens.