Previously white LEDs had a max of about 60 lumens per watt but the new White LEDs have 135 lumens per watt and match the best lighting alternatives
The new LED can replace traditional fluorescent bulbs for all general lighting applications, and also be used for automobile headlights and LCD backlighting.
Journal of Physics D: Applied Physics – White light emitting diodes with super-high luminous efficacy
We fabricated three types of high luminous efficacy white light emitting diodes (LEDs). The first was a white LED with a high luminous efficacy (ηL) of 249 lm W−1 and a high luminous flux (phiv) of 14.4 lm at a forward-bias current of 20 mA. This ηL was approximately triple that of a tri-phosphor fluorescent lamp (90 lm W−1). The blue LED used as the excitation source in this white LED had a high output power (phie) of 47.1 mW and a high external quantum efficiency (ηex) of 84.3%. The second was a high-power white LED, fabricated from the above high-power blue LED, and had a high phie of 756 mW at 350 mA. phiv and ηL of the high-power white LED were 203 lm and 183 lm W−1 at 350 mA, respectively. The third was a high-power white LED fabricated from four high-power blue LED dies. phiv and ηL of the high-power white LED were 1913 lm and 135 lm W−1 at 1 A, respectively. The white LED had a higher flux than a 20 W-class fluorescent lamp and 1.5 times the luminous efficacy of a tri-phosphor fluorescent lamp (90 lm W−1)
With these design improvements and the resulting enhancements in luminous efficacy, the new white LEDs provide further evidence that solid-state lighting can meet a wide variety of our future lighting requirements. Narukawa said that, although these LEDs are expensive compared to commercialized LEDs, he predicts that the price will come down in the future. He also plans to further enhance the luminous efficacy of the white LEDs for general lighting applications
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