LED light sources and solar cells are both on the verge of price thresholds that should make them everyday household products, and suddenly, a lot of scientists and engineers believe they have come up with the one technological breakthrough that will make the difference. In the process, they are showing us how similar the two technologies are.
For example, in both LEDs and photovoltaics, there is a lot of excitement this month about new techniques for manufacturing tiny ridges and grooves in the panel surface. The subtle variations in the surface shape, if formed precisely enough, make the light transfer more efficient, and it doesn’t particularly matter whether we’re talking about light going out or light coming in.
LEDs, of course, convert electricity to light; photovoltaics convert light to electricity. Both are manufactured as flat panels with lithographed electrical grids and other techniques in common. I am starting to wonder how long it might be before someone figures out a way to combine the two technologies, to make a single panel that converts light to electricity in the daytime and converts electricity to light at night. Or, a panel that converts light to electricity on the top surface and converts electricity to light on the bottom surface.
A device that converts energy from one form to another is a transducer. The idea of turning a transducer around is not new. Microphones and loudspeakers are also transducers, and any smallish loudspeaker, such as the ones you find in headphones, can also be used as a microphone, and some famous pop vocal tracks have been recorded this way as a special effect, using headphones as microphones.
Whether LEDs and photovoltaics achieve the same degree of reversibility or not, it sees likely enough that they will end up using much of the same manufacturing technology. This means that some of the breakthroughs in generating electricity will also serve as breakthroughs in saving electricity.