how efficient they are and how bright they are are not the same thing
pico watt is quote a small unit of electricity [ one milion million of a watt or 10-12]
I wonder if the human eye can see the light from them
EDIT: from your second link
You guys all know that 69 picowatts of light is 6.9 x 10 to the -11 watts of light, right? It’s the same power output as a single cell in your body. It’s almost nonexistant. Normal LEDs use about 3 watts, that’s 3,000,000,000,000 picowatts!