Narrow Emission QD’s Improve Warm White LED Performance and Improve Color Rendering
Dr. Bhardwaj pointed out that red QDs with tunable peak emission and narrow FHWM in combination with a conventional phosphor material can lead to LED conversion efficiency improvements of 5% to 15% over commercial phosphor based LEDs at CCTs ranging from 5,000 to 2,700 K.
QD based LEDs have shown promise for over a decade after the first demonstration of color conversion with a blue LED. The combination of narrow full width at half-maximum (FHWM) and tunable peak wavelength of red QDs has resulted in 17% efficiency improvement of QD based LEDs compared to commercial red nitride based LEDs. The LED stability with 20 W∕cm2 of incident blue light and QD temperatures over 110°C have passed 3,000 h and continue to show no degradation.
Figure 1: Improved CE and CRI by eliminating the light outside the photopic (eye) response. Up to 10-20% performance improvement especially for CRI 90.
Figure 2: LUXEON 3535L HE PLUS – First mass-produced QD LED will be launched within the next months.
Figure 3: Emission spectrum comparison. Conventional phosphor (top), QD LEDs (bottom).
“The QD emission wavelength can be tuned by the size of the particle. This huge improvement will lead to 50% reduction of the number of LEDs needed for a given system and specification”, said Dr. Jy Bhardwaj at the Lightfair International in Philadelphia.