One of the drawbacks of traditional silicon-based photovoltaic cells is that they are hard. While it's possible to embed traditional solar cells in fabric, it's not an optimal situation -- the cells themselves remain solid, even if the fabric is flexible. The backing electronics required for silicon cells adds further complexity to using them as anything other than a standalone add-on for devices or buildings. But what if the photovoltaics were made of something other than silicon?
Organic photovoltaics are flexible, lightweight, and potentially less expensive than traditional solar cells (they're "organic" because they're based on carbon). The main drawback is that organic PV cells are nowhere near as efficient at converting light into electricity as silicon cells. A recent development at Georgia Institute of Technology, however, is starting to close that performance gap. By adding a chemical called pentacene to the carbon "buckyballs" (Fullerenes again!) used in making the organic solar cells, the researchers were able to boost the efficiency to nearly 3.4 percent, with signs they could get to 5 percent in the near future. This compares to 25 percent for silicon cells (and up to 50 percent for experimental materials).
Although organic solar cells aren't as efficient, their other characteristics -- flexibility, weight, ruggedness, cost -- still make them attractive. They can be more readily embedded in other materials, from fabrics to plastics to roofing, and are ideal for small, low-power projects such as remote sensors. If, a decade from now, you drive a car with solar cells on its roof to help recharge the hybrid batteries, these are mostly likely the cells you'll be using.
