Transparent solar panels — think about it for a moment: Sheets of transparent glass or plastic film that also generate electricity. It’s almost the perfect solution for all our energy needs, generating free power from every available surface, window, and computer display.
The concept of transparent solar panels isn’t new, of course, but it now looks like they’re finally finding their way to market: Ubiquitous Energy, a startup that was spun off from MIT last year, is developing a technology and patent portfolio and hopes to bring affordable transparent solar panels to market soon.
At this point, you might be wondering how transparent solar cells actually work — after all, if it’s transparent, how can it absorb light energy? The simple answer is that light energy comes in many frequencies (colors), but as far as we humans are concerned, it is only the visible wavelengths — from blue, through green and yellow, to red — that really matter. The Sun, however, pumps out a huge amount of infrared light, and some ultraviolet light — both of which are invisible to the human eye, but which can also generate large amounts of electricity if captured by a solar cell.
The trick, then, is creating a solar cell that only absorbs IR and UV radiation, while letting visible light pass straight through. According to Technology Review, Ubiquitous Energy’s transparent solar cell is built up from a series of organic layers on glass or a flexible film. We don’t know the exact nature of the organic materials being used, but other organic solar cells generally use organic polymers that might’ve had their molecular makeup altered to absorb specific wavelengths of light. There are other ways of building transparent solar cells, though: As we reported last year, researchers at UCLA and UC Santa Barbara made a flexible, high-efficiency cell from a mesh of transparent, photovoltaic silver nanowires.
So far, as of a paper published in 2011 (linked below), it seems Ubiquitous Energy has created solar cells that are around 60% transparent, with an efficiency of 2%. The ultimate goal, as with all bleeding-edge solar tech, is to reach 10% efficiency, which is where really exciting applications tend to emerge. To get there, Ubiquitous Energy’s co-founder says his company will optimize its photovoltaic materials to capture more of the deeper infrared spectrum, and employ nanoscale engineering to create structures that capture more light. (See: Princeton’s nanomesh nearly triples solar cell efficiency.)
The applications for transparent solar cells, as you’ve probably imagined by now, are rather extensive. For a start, you could cover every car, home, and office window in solar cells — it wouldn’t replace the power grid, but it would provide enough free electricity to power the lights, or a few computers. The most interesting use, though, is on smartphone, tablet, and e-reader displays: If Ubiquitous Energy can reach transparency levels upwards of 80 or 90%, your smartphone could gather power from the Sun — and also harvest power from the device’s own backlight. Because Ubiquitous Energy’s solar panels absorb UV light, they would also make the perfect material for sunglasses — and powering yourwearable computer, perhaps.