Scientists from the University of Cambridge have led the development of the next-generation smart lighting system using a combination of nanotechnology, color science, advanced computational methods, electronics, and a unique fabrication process. They come up with smart, color-controllable white light devices from quantum dots.
Using more than three primary lighting colors used mainly in LEDs, scientists could produce daylight more accurately. When tested, the system demonstrated excellent color rendering, a wider operating range than current smart lighting technology, and a wider spectrum of white light customization.
Since the 1990s, quantum dots have been researched and developed as light sources because of their excellent color purity and tunability. They exhibit great color performance in both wide color controllability and high color rendering capabilities because of their distinctive optoelectronic features.
Scientists developed an architecture for quantum-dot light-emitting diodes (QD-LED) based on next-generation bright white lighting. They combined system-level color optimization, device-level optoelectronic simulation, and material-level parameter extraction to do so.
They developed 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 quantum dots that scientists used were between three and 30 nanometres in diameter. By choosing quantum dots of a specific size, they were able to overcome some of the practical limitations of LEDs. Doing so also helped them 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 wide spectrum of white light shade customization.
The newly designed QD-LED system showed a correlated color temperature (CCT) range from 2243K (reddish) to 9207K (bright midday sun), compared with current LED-based smart lights, which have a CCT between 2200K and 6500K. The color rendering index (CRI) – a measure of colors illuminated by the light in comparison to daylight (CRI=100) – of the QD-LED system was 97, compared to current smart bulb ranges, between 80 and 91.
The design might open the door to smart lighting that is more precise and efficient. Each of the three LEDs must be separately regulated to produce a specific color in an LED smart bulb. All of the quantum dots are driven by a single common control voltage to accomplish the whole color temperature range in the QD-LED system.
Professor Jong Min Kim from Cambridge‘s Department of Engineering, who co-led the research, said, “This is a world-first: a fully optimized, high-performance quantum-dot-based smart white lighting system. This is the first milestone toward fully exploiting quantum-dot-based smart white lighting for daily applications.”
Professor Gehan Amaratunga, who co-led the research, said, “The ability to better reproduce daylight through its varying color spectrum dynamically in a single light is what we aimed for. We achieved it in a new way by using quantum dots. This research opens the way for various new human responsive lighting environments.”
- Samarakoon, C., Choi, H.W., Lee, S. et al. Optoelectronic system and device integration for quantum-dot light-emitting diode white lighting with computational design framework. Nat Commun 13, 4189 (2022). DOI: 10.1038/s41467-022-31853-9