Most Light Emitting Diodes (LEDs) we use are tiny – alert, signal or decorative lights on computers, stereos and other electronics, small strings of lights, makeup and (more and more commonly) t-shirts.
Ginned up into full-sized bulbs they're ridiculously expensive but wickedly efficient, making a growth industry out of the research required to make their expense less ridiculous or efficiency more wicked.
LED bulbs use far less electricity per unit of light produced than either incandescent or fluorescent bulbs, but they still produce some heat which, as with most light sources, is considered to be a largely unavoidable waste product.
LEDs are semiconductors built with atomic lattices full of "electron holes" – spots in an atomic structure that would normally hold an electron but, in this case, don't.
When you switch on an LED, its electrons make a beeline for the electron holes, releasing energy as they split from their old spots and head toward the new.
That energy manifests as streams of photons which we see as light. The color of the light depends on the amount of energy it takes to release electrons from their orbits around one nucleus so they can carry a charge elsewhere.
Electrons steal heat to pay for travel to a different electron hole
Normally, if you want something to shine more brightly, you increase the energy pumped into it.