University of Cambridge develops quantum dot-based LED smart lighting system

By using quantum dots - tiny semiconductors just a few billionths of a meter in size - researchers have designed smart, color-controllable white light devices that are more efficient than standard LEDs, have better color saturation and can dynamically reproduce daylight conditions in a single lamp.

Researchers from the University of Cambridge have designed the next generation of smart lighting systems using a combination of nanotechnology, color science, advanced computational methods, electronics and unique manufacturing processes.

The research team found that by using more than the three main lighting colors used in typical LEDs, they were able to more accurately reproduce daylight. Early testing of the new design shows excellent color rendering, a wider operating range and a wider customizable spectrum of white light than current smart lighting technologies. These results were recently published in Nature Communications.

As the availability and characteristics of ambient light are related to health, the spread of smart lighting systems can have a positive impact on human health because these systems can respond to personal emotions. In addition, smart Lighting also responds to circadian rhythms, regulating daily sleep-wake cycles, so light is red-white in the morning and evening and blue-white during the day.

When a room has enough natural or artificial light, has good glare control, and has a view of the outdoors, then it can be said to have good visual comfort. In indoor environments under artificial light, visual comfort depends on the accurate representation of colors. Since the color of an object is determined by illumination, smart white light lighting needs to be able to accurately express the color of surrounding objects. Current technology achieves this by using three different colors of light simultaneously.

Quantum dots have been researched and developed as light sources since the 1990s due to their high color tunability and color purity. Due to their unique optoelectronic properties, they exhibit excellent color performance in terms of broad color controllability and high color rendering.

Researchers at the University of Cambridge have developed an architecture for the next generation of smart white lighting based on quantum dot light-emitting diodes (QD-LEDs). They combine system-level color optimization, device-level optoelectronic models Simulation is combined with material-level parameter extraction.

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Researchers generated a computational design framework from color optimization algorithms for neural networks in machine learning, along with a new method for modeling charge transport and light emission.

QD-LED systems use multiple primary colors—beyond the commonly used red, green, and blue—to more accurately simulate white light. By choosing quantum dots of a specific size -- between 3 and 30 nanometers in diameter -- the researchers were able to overcome some of the practical limitations of LEDs and achieve the emission wavelengths they needed to test their predictions.

The team then validated their design by creating a new device architecture for white lighting based on QD-LEDs. Test results show excellent color rendering, a wider operating range and a wider spectrum of white light shade customization than current technology.

QD-LED systems developed at the University of Cambridge display correlated color temperatures (CCT) ranging from 2243K (reddish) to 9207K (bright midday sunlight), while current LED-based smart lights have CCTs between 2200K and 6500K. Color rendering index of QD-LED systems (CRI) - the color that a lot of light illuminates compared to daylight (CRI=100) - is 97, while current smart bulbs range from 80 to 91.

The design could pave the way for more effective and accurate smart lighting. In an LED smart light bulb, three LEDs must be controlled individually to achieve a specific color. In a QD-LED system, all quantum dots are driven by a common control voltage to achieve a full color temperature range.

Professor Jong Min Kim from the Department of Engineering at the University of Cambridge said: "This is a world first: a fully optimized, high-performance quantum dot-based smart white lighting system. This is the first milestone towards the full utilization of quantum dot-based smart white lighting for everyday applications."

Gehan, who co-led the research Professor Amaratunga said: "The ability to dynamically and better reproduce daylight through its different color spectrum in one lamp was our goal. We achieved this in a new way by using quantum dots. This research opens the door to a variety of new human-responsive lighting Open the way to brighten the environment. ”

The structure of the QD-LED white lighting developed by the Cambridge University team can be extended to a large lighting surface because it is made using a printing process and its control and driving are similar to those in displays. Since standard point source LEDs need to be controlled individually, this is a more complex task.