[Analemma_]

Yes, it's drawing heat from the environment: the diode itself gets cooler as it emits light, and presumably at some point there's no more available energy in this way and so efficiency goes back below 100%

[thmsths]

Which is still amazing. An issue with high power LED is cooling. If this can be turned into a product, it solves the issue in the best possible way.

[thfuran]

It can't for high power LEDs.

[dzhiurgis]

What if you point light into solar panel and use the power for LED..?

Or point the light to space for a space cooler (IIRC I've read about something like this before).