Technical / research

Stacked-RGB microLED microdisplay developed Sundiode announced that it has achieved the successful growth of a monolithic, all-InGaN RGB LED structure on a single sapphire wafer. This structure was developed in collaboration with Soft-EPI.

Image

Sundiode's epitaxial technology enables stacked-RGB LEDs with multiple junctions, capable of emitting RGB colors independently. This structure makes it easier to produce ultra-high density microdisplays.

Toshiba Corporation announced that it has developed a new high-performance phosphor material that could be highly useful in microLED color conversion, among other applications. Toshiba aims to start mass producing the new material in 2025, and will soon offer samples for potential partners and customers.

Image

Toshiba says that the new material delivers excellent solubility in polymers or organic solvents, where it is transparent and colorless under visible light, and that emits persistent red-light emissions under UV light, with excellent color purity and a luminescence six times that of current phosphors.

Researchers from Korea-based KAIST institute developed a microLED-powered wearable patch that acts as an UV-induced inhibitor for melanogenesis, the creation of brown or dark pigments that can lead to skin diseases.

Image

LEDs have been used to photo-stimulate in skin care, but normal devices cannot conform to the skin shape, they operate from a distance which is problematic. If the patch is connected to the skin, it achieves much more effective photo-treatment. In this research, the team fabricated a 4x4 cm² wearable device made from an array of 100-micron sized microLED chips, vertically interconnected for high flexibility.

Kyocera Corporation announced that it has successfully developed a new process technology to produce microLED (and micro-laser) devices. The process is based on lateral growth of GaN layer on a silicon wafer, in a way that limits defects in most of the area.

Image

The basic process has three steps. First you grow a GaN layer on silicon. The second step is to apply a mask with a has a horizontal gap. The third step is to continue growing the GaN layer. The defects are concentrated in the opening nucleus, but the rest of the growth area remains almost defect free. The actual microLED devices are fabricated from the low-defect region.

The COVID-19 pandemic created an increased demand for high quality IT solutions, including monitors and collaborative tools, which prompted LCD and OLED display makers to develop new solutions for this market for applications like computer monitors, signage and more.

microLED displays (and also OLED displays) that are 20-inch or more will suffer from incompatibility with standard capacitive touch, because the thin microLED display panels result in large parasitic capacitive coupling with the touch surface. The dynamic driving of microLED (where only lit pixels draw current) further reduces the capacitive touch performance by introducing unpredictable “display pattern noise”. These issues are easily mitigated in small area displays, but as displays increase in size, the performance and costs of capacitive solutions suffer.

QustomDot and MICLEDI announced a joint  development program to develop color microLED microdisplays using QustomDot's color conversion technology. The companies will demonstrate a microdisplay that offers a new architecture tailored for high-efficiency color conversion using stable RoHS-compliant QD materials. The displays will be produced using a high-throughput QD transfer and patterning techniques on micron-sized pixels.

QustomDot developed a patented method to produce high-quality and stable QD materials suitable for microLEDs. MICLEDI is producing its microdisplays on 300 mm wafers, and the company developed a new pixel architecture that has been optimized for high-aperture (>60% aperture at a 3μm pixel pitch) which the company says is a key requisite to achieve a high brightness with quantum dots.

UK-based Kubos Semiconductors raised $605,000 to launch its cubic-GaN LED technology into new markets, such as microLED displays.

Image

Kubos says that its unique cubic-GaN technology can increase light output (and efficiency) of green LEDs. Kubos operates in a fabless model and says that its technology is fully compatible with standard LED development process on large wafers, offering lower cost volume production. Kubos is also looking to use the technology to produce red GaN LEDs.

LED display market Leyard Optoelectronics announced that it developed the world's first mass-produced microLED display that uses quantum dots color conversion technology. Leyard collaborated with Saphlux (of which it owns around 12%).

Leyard adopted Saphlux's NPQD R1 micro LED technology, and have completed the development and testing of the display technology, and now it can mass produce NPQD-powered displays.

Researchers from the Beijing Institute of Technology and MIIT have developed perovskite quantum dots microarrays with strong potential for quantum dots color conversion (QDCC) applications including micro-LEDs displays.

Perovskite quantum dots (PQDs) hold potential as an attractive material and can resolve some of the problems found in conventional QDCC. While perovskite quantum dots are relatively new, they have already been shown to have attractive properties that make them extremely suited for electronic and optoelectronic applications.