jtr1962
Flashaholic
See the abstract here. A few of their numbers are very interesting. The first sample was 161 lm/W and 9.89 lm at 20 mA. This implies a forward voltage of 3.071V and an input power of 61.4 mW. They mentioned the output of the blue chip used in this LED was 42.2 mW, hence a WPE of 68.7%. This is the highest WPE I've ever heard for a blue LED.
The second sample is the one which achieved 169 lm/W. I found it interesting that they consider ~2.8V as nearly equal to the theoretical limit for the blue emitter used. Assuming similar phosphor conversion efficiencies as the 161 lm/W sample, this blue LED has achieved efficiencies of roughly 72%. In my opinion, most of the 28% which is not converted to light is probably simply not being extracted. In any case these lab results show that 75% to 80% emitter efficiency should be achievable in the near future, at least with blue. If this can be done with green and reds, then 300+ lm/W RGB-based white is possible.
The power LED results were also interesting. At 134 lm/W they break Cree's record. The blue emitter has an output of 651 mW, for an overall efficiency of just over 60% at 350 mA. That's not much worse than their 20 mA results. In any case it looks like the 150 lm/W barrier will soon be broken for power LEDs, and we're closing in on 200 lm/W for indicator-type LEDs.
The second sample is the one which achieved 169 lm/W. I found it interesting that they consider ~2.8V as nearly equal to the theoretical limit for the blue emitter used. Assuming similar phosphor conversion efficiencies as the 161 lm/W sample, this blue LED has achieved efficiencies of roughly 72%. In my opinion, most of the 28% which is not converted to light is probably simply not being extracted. In any case these lab results show that 75% to 80% emitter efficiency should be achievable in the near future, at least with blue. If this can be done with green and reds, then 300+ lm/W RGB-based white is possible.
The power LED results were also interesting. At 134 lm/W they break Cree's record. The blue emitter has an output of 651 mW, for an overall efficiency of just over 60% at 350 mA. That's not much worse than their 20 mA results. In any case it looks like the 150 lm/W barrier will soon be broken for power LEDs, and we're closing in on 200 lm/W for indicator-type LEDs.
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