Tofu ingredient could clean up solar cell recipe

Dr Jon Major says magnesium chloride could replace toxic cadmium chloride in CdTe solar cells without impacting efficiency

Tofu has long been touted as a good way to clean out your insides, but now a researcher at the University of Liverpool says an ingredient in tofu could also be used to clean up solar cells. The hope is that the naturally occurring substance could replace a key ingredient in thin film solar cells that is highly toxic and expensive to produce.

Conventional manufacture of thin film solar cells requires sophisticated safety measures to protect workers from the hazards presented by cadmium chloride, a key ingredient in thin film solar cell technology. Additionally, once the solar cells have reached the end of their life, specialist disposal is required to deal with the highly toxic soluble compound.

Despite these shortcomings, its benefit is improved solar efficiency. By applying it to the cheapest kind of solar cells that are based on a thin film of insoluble cadmium telluride (CdTe), conversion efficiency jumps from under two percent to over 15 percent.

Now, Dr Jon Major, a physicist working at the University of Liverpool's Stephenson Institute for Renewable Energy, says cadmium chloride could be replaced by magnesium chloride, a compound that can be extracted from seawater and already has a wide variety of applications. These include, being used for de-icing roads, as a fertilizer, as a mineral supplement for animals, in fire extinguishers and acting as a coagulant in the preparation of tofu from soy milk.

Adding to the long list of uses, Major claims that magnesium chloride can produce the same boosts in conversion efficiency as provided by cadmium chloride, while being much safer.

"We have to apply cadmium chloride in a fume cupboard in the lab, but we created solar cells using the new method on a bench with a spray gun bought from a model shop," says Major.

Additionally, Major says magnesium chloride is much cheaper, costing US$0.001 per gram compared to $0.3 per gram for cadmium chloride.

"Cadmium chloride is toxic and expensive and we no longer need to use it," adds Major. "Replacing it with a naturally occurring substance could save the industry a vast amount of money and reduce the overall cost for generating power from solar."

Dr Major's study is published in the journal Nature.

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