Quantum dots enable red microLED for smart glasses display
Mojo Vision in the US has developed the world’s highest density red microLED microdisplay with a resolution of 14K ppi using quantum dots.
A red microLED display is an important step in overcoming challenges of delivering high-performance and reliable full-colour displays.
The red microLEDs measure 1.37um in diameter and are set on a 1.87um pitch. This visual quality is critical in meeting the full-colour requirements for augmented reality (AR) and extended reality (XR) markets.
The ability to make very small red, green, and blue micro-LEDs on the same substrate is critical to achieving vibrant and effective full colour microdisplays,” said Dr. Nikhil Balram, chief executive officer of Mojo Vision. “Powering a true red display, rather than leaning toward orange as others do, at this size and specification puts us a big step closer to producing a micro-LED display that will meet or exceed the current performance and form factor requirements for AR and XR products.”
While it is typically easier to deliver high-quality micro-LEDs at larger sizes (> 5um), the industry has struggled with smaller micro-LEDs, particularly those using colour conversion materials. Mojo Vision’s development is a record pitch exceeding past records for red wavelengths of 620n or more that are required by major colour standards used in broadcast and consumer displays.
“Addressing all three comfort pillars — wearable, visual and social — in all-day use smart glasses is critical for wide consumer adoption,” said Dr Bernard Kress, president of the International Society for Optics and Photonics (SPIE). “The display sub-system is at the core of this problem. Emissive display panels are preferred to traditional liquid crystal on silicon (LCOS) or digital light processing (DLP) panels that require larger volumes and higher drive power. Although micro-OLED panels can be effectively matched to bulky birdbath combiners, micro-LED panels are best suited for thin waveguide combiners due to their higher brightness.
“Monolithic RGB micro-LED panels have been the industry’s holy grail for many years now but are still struggling to produce efficient pixels with pitches below four microns, with challenges ranging from using InGaN instead of more mature AlInGap, efficiency in red, reliability and thermal issues, and lack of 300mm wafer scale fab,” said Kress. “Mojo’s proprietary red and green QD conversion of mature blue GaN micro-LED panel technology at pixel pitches below two microns can be a great alternative and provide effective solutions for today’s smart glasses.”
Mojo Vision’s prototype will support a more advanced display in lightweight glasses form factor. The company recently announced a partnership with DigiLens to advance display capabilities in AR/XR markets. The partnership comes on the heels of Mojo Vision’s successful light-up of the first-ever 300mm blue GaN-on-Silicon micro-LED array wafer.
“Full colour micro-LED microdisplays are going to start emerging in the market in the coming years,” said Dr. Guillaume Chansin, director of Display Research at Display Supply Chain Consultants (DSCC). “Mojo Vision’s prototype stands out as a new milestone, by demonstrating red colour conversion with a sub-2um pixel pitch. This development is significant for the micro-LED industry and shows the potential of Mojo Vision’s approach towards full colour, high resolution microdisplays.”
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