3 ms·

The theoretical efficiency of LEDs is definitely not 40%. LED efficiency has been measured to be 230% with 30 picowatt power consumption: https://www.google.co

• nkurz 10y ago
  Their claimed efficiency is only sort of true, in that it's measuring the electrical input while ignoring the external heat also used to run the light. By similar logic, one could say that a steam engine running in a very hot room is also over 100% efficient. Also, the "theoretical efficiency of LEDs" is a very different number than the "theoretical efficiency of white LEDs". I think when talking about white LEDs, they are assuming a monochromatic LED pumping a phosphor. But while it's not that practical, in that it's limited to picowatts (10^-12 watts), it is interesting nonetheless. Another similarly surprising example is that the theoretical maximum efficiency of some fuel cells also exceeds 100%, for similar reasons of extracting heat from the environment.