Thin-film solar cells promise to bring flexible, low-profile solar power to all kinds of surfaces. Unfortunately, constructing thin-film panels requires cadmium chloride, a finicky, expensive, and toxic material. Now, University of Liverpool scientists have figured out how to make solar cells using magnesium chloride, a compound so innocuous, it's actually used in the production of tofu.
While coating a solar cell with a solution of cadmium chloride greatly boosts the cell's energy production, the production process is toxic, potentially carcinogenic, and very expensive—cadmium ions can be carried away in water during production, requiring waste water to be thoroughly filtered and workers to wear protective gear. Fortunately, the layer of cadmium in the finished solar cell isn't toxic, but getting to that point is difficult.
University of Liverpool physicist Jon Major and colleagues set out to test other types of salts to see if they could find an effective, nontoxic replacement for cadmium chloride. They settled on magnesium chloride, which is used to coagulate soy milk into tofu, as an ingredient in bath salts (the beauty product, not the illicit drug), and as a road de-icer.
It turns out, magnesium chloride is just about equally effective when compared to cadmium chloride. It's piles cheaper (by a factor of three hundred), requires no elaborate environmental protection or safety gear, and can be applied using simple sprayers rather than the elaborate sputter deposition equipment required for cadmium chloride.
Of course, as folks in the solar panel industry point out, simply finding a cheaper ingredient doesn't necessarily make for a cheaper final product: building solar panels is still an expensive proposition. But there's something straight up awesome about the notion that you can replace a highly toxic, difficult compound with something you can get off the shelf of Bath & Body Works, without a reduction in efficiency. Makes you wonder why we ever used the toxic stuff to begin with. [Nature; University of Liverpool via Ubergizmo]
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