LED Smart Lighting System Based on Quantum Dots More Accurately Reproduces Daylight – SciTechDaily
Researchers have designed smart, color-controllable white light devices from quantum dots – tiny semiconductors just a few billionths of a meter in size – which are more efficient and have better color saturation than standard LEDs, and can dynamically reproduce daylight conditions in a single light.
The researchers, from the University of Cambridge, designed the next-generation smart lighting system using a combination of nanotechnology, color science, advanced computational methods, electronics, and a unique fabrication process.
The team found that by using more than the three primary lighting colors used in typical LEDs, they were able to reproduce daylight more accurately. Early tests of the new design showed excellent color rendering, a wider operating range than current smart lighting technology, and wider spectrum of white light customization. The results are reported today (August 3) in the journal Nature Communications.
As the availability and characteristics of ambient light are connected with wellbeing, the widespread availability of smart lighting systems can have a positive effect on human health since these systems can respond to individual mood. Smart lighting can also respond to circadian rhythms, which regulate the daily sleep-wake cycle, so that light is reddish-white in the morning and evening, and bluish-white during the day.
When a room has sufficient natural or artificial light, good glare control, and views of the outdoors, it is said to have good levels of visual comfort. In indoor environments under artificial light, visual comfort depends on how accurately colors are rendered. Since the color of objects is determined by illumination, 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 simultaneously.
Quantum dots have been studied and developed as light sources since the 1990s, due to their high color tunability and color purity. Due to their unique optoelectronic properties, they show excellent color performance in both wide color controllability and high color rendering capability.
The Cambridge researchers developed an architecture for quantum-dot light-emitting diodes (QD-LED) based next-generation smart white lighting. They combined system-level color optimization, device-level optoelectronic simulation, and material-level parameter extraction.
The researchers produced a computational design framework from a color optimization algorithm used for neural networks in machine learning, together with a new method for charge transport and light emission modeling.
The QD-LED system uses multiple primary colors – beyond the commonly used red, green, and blue – to more accurately mimic white light. By choosing quantum dots of a specific size – between three and 30 nanometres 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 of QD-LED based white lighting. The test showed excellent color rendering, a wider operating range than current technology, and a …….