By using quantum dots -- tiny semiconductors only a few billionths of a meter in size -- researchers have designed smart, color-controllable white light devices that are more efficient and colorful than standard LEDs. Better saturation and dynamic reproduction of daylight conditions in one light.

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 a unique manufacturing process.

The team found that by using more than the three primary lighting colors used in typical LEDs, they were able to more accurately reproduce sunlight. Early tests of the new design have shown excellent color rendering, a wider operating range and a wider custom white light spectrum than current smart lighting technologies. These results have been published in Nature Communications.

Since the availability and properties of ambient light are health-related, the proliferation of smart lighting systems can have a positive impact on human health, as these systems can respond to individual emotions. In addition, smart lighting can also respond to circadian rhythms, regulating the daily sleep-wake cycle, so the light is red and white in the morning and evening, and blue and white during the day.

A room is said to have good visual comfort when it has sufficient natural or artificial light, good glare control, and a view of the outdoors. In indoor environments under artificial light, visual comfort depends on how accurately colors are rendered. Since the color of an object is determined by illuminance, smart white lighting needs to be able to accurately express the color of surrounding objects. Current technology achieves this by using three different colors of light at the same time.

Due to their high color tunability and color purity, quantum dots have been researched and developed as light sources since the 1990s. 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 simulation, and material-level parameter extraction.

Cambridge University develops quantum dot-based LED smart lighting system

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The researchers generated a computational design framework from a color-optimization algorithm 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 specific sizes of quantum dots -- between 3 and 30 nanometers in diameter -- the researchers were able to overcome some of the practical limitations of LEDs and achieve their desired emission wavelengths to test their predictions.

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

QD-LED systems developed at the University of Cambridge display correlated color temperatures (CCTs) ranging from 2243K (reddish) to 9207K (bright midday sunlight), while current LED-based smart lights have CCTs between 2200K and 6500K. The QD-LED system's Color Rendering Index (CRI) -- a measure of the color illuminated by light compared to daylight (CRI=100) -- is 97, while current smart bulbs range from 80 to 91.

The design could pave the way for more efficient and accurate smart lighting. In LED smart bulbs, the three LEDs must be individually controlled 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 University of Cambridge's Department of Engineering said: "This is a world first: a fully optimised, high-performance quantum dot-based smart white lighting system. This is the first to fully utilize quantum dot-based smart white lighting Milestones that can be used in everyday applications."

Professor Gehan Amaratunga, who co-led the study, said: "The ability to dynamically better reproduce sunlight in a lamp through its different colour spectrums was our goal. We achieved this in a new way by using quantum dots. This. This research opens the way for a variety of new human-responsive lighting environments."

The structure of the QD-LED white lighting developed by the University of Cambridge team can be extended to large illuminated surfaces because it is fabricated using a printing process and its control and actuation are similar to those in displays. This is a more complex task as standard point source LEDs need to be individually controlled. (Source: cnBeta)