Saphlux Brightens AR/VR Micro-LED Displays With Nanoporous Quantum Dots

August 23, 2023 by Jake Hertz

Using modified quantum dot technology, Saphlux says its new display prototype offers the best red micro-LED engine in the industry.

Last week, Connecticut-based startup Saphlux demonstrated a new micro-LED display based on a patented technology called nanoporous quantum dots (NPQD).


Saphlux micro-LED display

Saphlux’s 0.39” micro-LED display. Image used courtesy of Saphlux


Spinning out of Yale University in 2015, Saphlux is known for its GaN-based light engine products, including its "industry's first" quantum dots-in-chip micro-LED technology for displays. With this 0.39” full-color micro-LED display, the company intends to innovate AR/VR beyond the capabilities of current micro-organic LEDs and liquid crystal on silicon (LCOS) alternatives. 


Saphlux Outshines Mainstream Displays With Micro-LEDs

Saphlux's new NPQD-based display runs on the company's T1-0.39 NPQD RGB light engine, which enables microLEDs with pixel pitches of less than two microns.

The prototype T1-0.12 NPQD red light engine

The prototype T1-0.12 NPQD red light engine. Image used courtesy of Saphlux

In demonstrations, the display achieved a maximum white brightness of 250,000 nits and a photon conversion efficiency of 67%. In contrast, the iPhone 14’s display achieves a peak brightness of 1,200 nits and comes in a 6.7” display. This makes Saphlux’s technology significantly brighter and higher performing than commercialized competitors—and the display comes in a much smaller area.


What Are Nanoporous Quantum Dots?

While Gallium Nitride (GaN) is already widely used in LEDs, Saphlux unlocked new functionality from the semiconductor by creating nanopores in it. The company forms these pores by dipping the material in an acidic solution and applying a specific bias voltage, driving an electrochemical etching process. They then carefully control the bias voltage and silicon doping concentration to precisely adjust the size and porosity of the nanopores.


Light conversion efficiency and photoluminescent intensity of quantum dots vs. NPQD

Light conversion efficiency and photoluminescent intensity of quantum dots vs. NPQD. Image used courtesy of Compound Semiconductor

Once these nanopores are created, they can be filled with quantum dots (QDs), semiconductor particles only a few nanometers in size. Quantum dots have unique optical properties, including a high quantum yield, size-dependent emission wavelength, and narrow emission linewidth. When embedded within GaN nanopores, they interact with the material in a way that significantly boosts their light conversion efficiency.

The strong scattering effect of nanoporous GaN increases the effective light path hundreds of times, leading to a tremendous increase in QD conversion efficiency and reliability. Compared to traditional quantum dot films, nanoporous GaN with embedded QDs can achieve light-conversion efficiency exceeding 80%, even with a film thickness of just 5 µm.


Saphlux Targets AR/VR Headset Displays

One of the major use cases that stands to benefit from Saphlux’s technology is augmented reality and virtual reality headsets (AR/VR). 

Many AR/VR glasses developers are designing products to be used for everyday uses outside of gaming, including in outdoor environments. These developers have traditionally faced challenges making AR/VR displays bright enough for outdoor use, specifically in red wavelengths. With an extremely high brightness of 250,000 nits, the Saphlux display may pave the way for a true outdoor-compatible display that can operate in any lighting condition. 

At the same time, the 67% quantum efficiency of Saphlux’s display has huge implications for energy efficiency and thermal management for AR/VR. By converting more power directly to usable light, the NQPD display can extend battery life and runtime for these devices, waste less energy on heat, and remain cooler and more comfortable for users.

Finally, the tiny pixel pitch of less than two microns means that NPQD technology enables extremely high-resolution displays. With these displays, AR/VR glasses can project more vivid and detailed images into the user’s eyes.


A Building Block Micro-LED Technology? 

Saphlux says its NPQD architecture even outperforms AlInGaP-based red micro-LED efficiency because it captures more blue photons and converts them into red. The architecture also shows lower thermal decay in the face of temperature. With these features, Saphlux called NPQD a "building block micro-LED technology" that will boost the potential of high dynamic range (HDR).

While the technology is still in the prototype phase, the company is offering samples and data upon request.