In the wave of display technology, there is an emerging technology that is quietly emerging, and it is called microLED. This flat panel display technology, which is composed of tiny light-emitting diodes, is leading a new revolution in the display field. Compared with existing liquid crystal displays (LCDs) and organic light-emitting diode (OLED) technologies, microLED display technology has higher brightness, better contrast, a wider color gamut range, and faster response time.
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MicroLED technology can first be traced back to 2000, when it was invented by the research group of Xingjiang Hong and Jingyu Lin at Kansas State University. In 2009, together with colleagues at Texas Tech University, they implemented the first high-resolution, video-driven VGA-resolution microLED microdisplay. This marks a critical step forward in microLED technology.
As a self-luminous display technology, each pixel of microLED is made up of tiny light-emitting diodes. These tiny LEDs are generally less than 50 microns in size and are therefore referred to as "micro" LEDs. Unlike LCDs, which require a backlight, microLED pixels emit light autonomously, allowing for precise brightness and color control.
MicroLED display technology offers many advantages, including high brightness, high contrast, wide color gamut, fast response time, and high energy efficiency. They can produce pure blacks by turning off individual pixels entirely, resulting in unmatched contrast. MicroLEDs also offer excellent color accuracy and a wider color range, making them ideal for applications that require vivid color reproduction.
In addition to excellent display performance, microLED technology is also scalable. By combining multiple microLED modules, it is possible to build large-format displays without compromising image quality or pixel density. This scalability makes microLED technology suitable for a wide range of applications such as large-screen TVs, digital signage, virtual reality (VR), augmented reality (AR), and wearables.
Challenges on the road to commercialization
Despite the promise of microLED technology, there are some significant challenges to overcome before it can be commercialized at scale. Manufacturing complexity is a big obstacle. MicroLED displays are made up of millions of tiny LEDs that need to be precisely placed and aligned, which places extremely high demands on the manufacturing process.
Another challenge is to achieve high yields. Due to the variety of defects that can occur during the manufacturing process, it is critical to ensure near-perfect display quality. It is estimated that for a microLED display to be commercially viable, the final product yield rate needs to exceed 99.9999% to minimize dead pixels.
The current high cost of microLED display technology is also a significant factor hindering its large-scale adoption. Complex manufacturing processes, low production volumes, and the challenges of scaling up production all contribute to the high cost of microLED displays. Achieving cost competitiveness with existing display technologies is key to commercializing microLED technology.
Nevertheless, industry experts believe that with the continuous advancement of technology and the gradual emergence of economies of scale, the cost of microLED display technology will gradually decrease, and eventually large-scale commercial production will be realized. Some companies have already begun to address these challenges to advance microLED technology.
Layout of foreign brands
Sony is a pioneer in the development of microLED technology. Back in 2012, Sony presented the world's first microLED TV prototype, which was named "Crystal LED" at the time. Although this 55-inch Full HD microLED TV ultimately didn't make it, Sony introduced a large-size outdoor microLED display in 2016 named "Canvas Display" or "CLEDIS".
Over the years, Sony has continued to introduce the new generation of CLEDIS displays and announced several large installations. In 2019, Sony began offering microLED Canvas displays for high-end residences. In addition to Sony, Samsung, TCL/CSOT, PlayNitride and other companies have also demonstrated microLED prototypes.
Samsung is a frontrunner in the commercialization of microLED technology. In 2021, Samsung has already started selling 110-inch 4K microLED TVs priced at $156,000. The TV has 8 million pixels and can display four 55-inch HD pictures at the same time.
In addition to large-format TVs, microLED technology is also seen as ideal for AR/VR head-mounted displays. With extremely high pixel density, brightness, and contrast, microLEDs can provide an unparalleled immersive visual experience for AR/VR devices.
Boston-based Mojo Vision is developing microLED-based AR contact lenses. In 2022, the company's former CEO, Drew Perkins, wore a prototype AR contact lens with an integrated 14,000ppi green microLED display. While this product was eventually canceled, Mojo Vision is working on a smaller, lighter, and more discreet microLED AR device.
The pace of catch-up of domestic manufacturers
In the development tide of microLED technology, domestic manufacturers are naturally not far behind. BOE, Epistar and other companies are planning to carry out mass production of microLED displays. As a leading microLED company in China, Jiangsu Jade Bird Display (JBD) has mass-produced a green monochrome microLED micro-display with a resolution of 640x480, which has been applied to AR glasses products from Vuzix, OPPO and other manufacturers.
JBD's microLED display currently only supports 4-bit color depth, which is 16 levels of brightness, and color levels occur when displaying smooth gradients. But the company says future designs will support higher color depths and improved displays. JBD has been working hard to improve the pixel-to-pixel brightness difference, but the visible "graininess" remains.
In addition to JBD, other domestic companies such as Nexperia and Visionox are also tirelessly forging ahead in the field of microLED technology. The development of the microLED industry in mainland China is in a critical period of climbing, and more innovative breakthroughs are needed to truly realize the domestic substitution of microLED technology.
The road to mass production still needs to be cleared
Looking at the history of microLED technology, it's easy to see that despite the strides made, there are still many hurdles to true large-scale commercialization. The luminous efficiency of red microLEDs has always been a challenge. Due to their tiny size, when the size of microLEDs is reduced, the brightness drops dramatically.
The high-precision transfer assembly of microLED chips is also a challenge. Currently, only a maximum of 5-40 chips can be transferred per second, and about 25 million transfers are required to make an 8K display, which is too slow and inefficient. Although some new transfer technologies have emerged in the industry, there are still many bottlenecks that need to be broken through to achieve high-throughput and high-precision transfer.
Testing and repairing microLED displays is also a challenge. Due to the tiny size of microLED chips, traditional test equipment cannot meet the demand. Regardless of whether photoluminescence (PL) testing or electroluminescence (EL) testing is employed, the efficiency is low and may cause chip damage.
MicroLED technology still faces many challenges in terms of manufacturing process, capacity, yield, cost, etc., and there is still a long way to go before it can be truly commercialized on a large scale. However, industry insiders generally expect that in the next 3-5 years, microLED technology will take the lead in achieving commercial breakthroughs in wearable devices, AR/VR head-mounted displays and other fields.